updated discover with alt text (#77660)

* Update context.asciidoc

* Update document-data.asciidoc

* Update field-filter.asciidoc

* Update search.asciidoc

* Update set-time-filter.asciidoc

* Update viewing-field-stats.asciidoc

* Update canvas-edit-workpads.asciidoc

* Update canvas-expression-lifecycle.asciidoc

* Update canvas-present-workpad.asciidoc

* Update canvas-share-workpad.asciidoc

* Update canvas-tutorial.asciidoc

* Update docs/canvas/canvas-share-workpad.asciidoc

* Update docs/canvas/canvas-share-workpad.asciidoc

* Update docs/canvas/canvas-tutorial.asciidoc

* Update docs/canvas/canvas-tutorial.asciidoc

* Update docs/canvas/canvas-tutorial.asciidoc

* Update docs/canvas/canvas-tutorial.asciidoc

* Update docs/discover/search.asciidoc

* Update docs/discover/set-time-filter.asciidoc

* Update docs/discover/viewing-field-stats.asciidoc

* Update docs/discover/field-filter.asciidoc

* Update docs/discover/document-data.asciidoc

Co-authored-by: Kaarina Tungseth <kaarina.tungseth@elastic.co>

Author: ncheckin

docs/canvas/canvas-edit-workpads.asciidoc

@@ -25,12 +25,12 @@ For example, to change the index pattern for a set of charts:
 Specify the variable options.
 
 [role="screenshot"]
-image::images/specify_variable_syntax.png[Specify the variable syntax]
+image::images/specify_variable_syntax.png[Image describing how to specify the variable syntax]
 
 Copy the variable, then apply it to each element you want to update in the *Expression editor*.
 
 [role="screenshot"]
-image::images/copy_variable_syntax.png[Copy the variable syntax]
+image::images/copy_variable_syntax.png[Image demonstrating expression editor]
 
 [float]
 [[apply-changes-to-the-entire-workpad]]
@@ -85,7 +85,7 @@ To use an element with the same functionality and appearance in multiple places,
 Select the element, then click *Edit > Clone*. 
 
 [role="screenshot"]
-image::images/clone_element.gif[Clone elements]
+image::images/clone_element.gif[Image showing how to clone elements]
 
 [float]
 [[move-and-resize-elements]]

docs/canvas/canvas-expression-lifecycle.asciidoc

@@ -30,7 +30,7 @@ The filtered <<demodata_fn, demo data>> becomes the _context_ of the next functi
 
 Let’s look at another expression, which uses the same <<demodata_fn, demodata>> function, but instead produces a pie chart.
 
-image::images/canvas-functions-can-take-arguments-pie-chart.png[Pie Chart, height=400]
+image::images/canvas-functions-can-take-arguments-pie-chart.png[Pie chart showing output of demodata function]
 [source,text]
 ----
 filters
@@ -47,7 +47,7 @@ If the expression stopped there, it would produce a `pointseries` data type as t
 The end result is a simple pie chart that uses the default color palette, but the <<pie_fn, pie>> function can take additional arguments that control how it gets rendered. For example, you can provide a `hole` argument to turn your pie chart into a donut chart by changing the expression to:
 
 
-image::images/canvas-functions-can-take-arguments-donut-chart.png[Donut Chart, height=400]
+image::images/canvas-functions-can-take-arguments-donut-chart.png[Alternative output as donut chart]
 [source,text]
 ----
 filters
@@ -83,7 +83,7 @@ You can substitute one function for another to change the output. For example, y
 
 Let’s change that last pie chart into a bubble chart by replacing the <<pie_fn, pie>> function with the <<plot_fn, plot>> function. This is possible because both functions can accept a `pointseries` data type as their _context_. Switching the functions will work, but it won’t produce a useful visualization on its own since you don’t have the x-axis and y-axis defined. You will also need to modify the <<pointseries_fn, pointseries>> function to change its output. In this case, you can change the `size` argument to `y`, so the maximum price values are plotted on the y-axis, and add an `x` argument using the `@timestamp` field in the data to plot those values over time. This leaves you with the following expression and produces a bubble chart showing the max price of each state over time:
 
-image::images/canvas-change-your-expression-chart.png[Bubble Chart, height=400]
+image::images/canvas-change-your-expression-chart.png[Bubble Chart, with price along x axis, and time along y axis]
 [source,text]
 ----
 filters
@@ -95,7 +95,7 @@ filters
 
 Similar to the <<pie_fn, pie>> function, the <<plot_fn, plot>> function takes arguments that control the design elements of the visualization. As one example, passing a `legend` argument with a value of `false` to the function will hide the legend on the chart.
 
-image::images/canvas-change-your-expression-chart-no-legend.png[Bubble Chart Without Legend, height=400]
+image::images/canvas-change-your-expression-chart-no-legend.png[Bubble Chart Without Legend]
 [source,text,subs=+quotes]
 ----
 filters

docs/canvas/canvas-present-workpad.asciidoc

@@ -18,7 +18,7 @@ image::images/canvas-autoplay-interval.png[Element autoplay interval]
 . To start your presentation, click *View > Enter fullscreen mode*.
 +
 [role="screenshot"]
-image::images/canvas-fullscreen.png[Fullscreen mode]
+image::images/canvas-fullscreen.png[Image showing how to enter fullscreen mode from view dropdown]
 
 . When you are ready to exit fullscreen mode, press the Esc (Escape) key.
 
@@ -33,7 +33,7 @@ To get a closer look at a portion of your workpad, use the zoom options.
 . Select the zoom option.
 +
 [role="screenshot"]
-image::images/canvas-zoom-controls.png[Zoom controls]
+image::images/canvas-zoom-controls.png[Zoom controls, also in view dropdown]
 
 [float]
 [[configure-auto-refresh-interval]]

docs/canvas/canvas-share-workpad.asciidoc

@@ -13,7 +13,7 @@ Create a JSON file of your workpad that you can export outside of {kib}.
 Click *Share > Download as JSON*.
 
 [role="screenshot"]
-image::images/canvas-export-workpad.png[Export single workpad]
+image::images/canvas-export-workpad.png[Export single workpad through JSON, from Share dropdown]
 
 Want to export multiple workpads? Go to the *Canvas* home page, select the workpads you want to export, then click *Export*.
 
@@ -26,7 +26,7 @@ If you have a subscription that supports the {report-features}, you can create a
 Click *Share > PDF reports > Generate PDF*.
 
 [role="screenshot"]
-image::images/canvas-generate-pdf.gif[Generate PDF]
+image::images/canvas-generate-pdf.gif[Image showing how to generate a PDF]
 
 For more information, refer to <<reporting-getting-started, Reporting from Kibana>>.
 
@@ -39,7 +39,7 @@ If you have a subscription that supports the {report-features}, you can create a
 Click *Share > PDF reports > Copy POST URL*.
 
 [role="screenshot"]
-image::images/canvas-create-URL.gif[Create POST URL]
+image::images/canvas-create-URL.gif[Image showing how to create POST URL]
 
 For more information, refer to <<automating-report-generation, Automating report generation>>.
 
@@ -58,7 +58,7 @@ beta[] Canvas allows you to create _shareables_, which are workpads that you dow
 To make sure that your data remains secure, the data in the JSON file is not connected to {kib}. Canvas does not display elements that manipulate the data on the workpad.
 +
 [role="screenshot"]
-image::canvas/images/canvas-embed_workpad.gif[Share the workpad on a website]
+image::canvas/images/canvas-embed_workpad.gif[Image showing how to share the workpad on a website]
 +
 NOTE: Shareable workpads encode the current state of the workpad in a JSON file. When you make changes to the workpad, the changes do not appear in the shareable workpad on your website.
 

docs/canvas/canvas-tutorial.asciidoc

@@ -30,7 +30,7 @@ The default Elastic logo image appears on the page.
 . To replace the Elastic logo with your own image, select the image, then use the editor.
 
 [role="screenshot"]
-image::images/canvas-image-element.png[]
+image::images/canvas-image-element.png[Image showing how to add the image element]
 
 [float]
 === Customize your data with metrics
@@ -70,7 +70,7 @@ You're now looking at the raw data syntax that Canvas uses to display the elemen
 .. Click *Run*.
 
 [role="screenshot"]
-image::images/canvas-metric-element.png[]
+image::images/canvas-metric-element.png[Image showing changes to the Canvas workpad]
 
 [float]
 === Show off your data with charts
@@ -96,7 +96,7 @@ To show what your data can do, add charts, graphs, progress monitors, and more t
 .. From the *Y-axis* drop-down lists, select *Value*, then select *taxless_total_price*.
 
 [role="screenshot"]
-image::images/canvas-chart-element.png[]
+image::images/canvas-chart-element.png[Image showing Canvas workpad with sample data graph]
 
 [float]
 === Show how your data changes over time
@@ -110,7 +110,7 @@ To focus your data on a specific time range, add the time filter.
 . To use the date time field from the sample data, enter `order_date` in the *Column* field, then click *Set*.
 
 [role="screenshot"]
-image::images/canvas-timefilter-element.png[]
+image::images/canvas-timefilter-element.png[Image showing Canvas workpad with filtered sample data graph]
 
 To see how the data changes, set the time filter to *Last 7 days*. As you change the time filter options, the elements automatically update.
 

docs/discover/context.asciidoc

@@ -16,7 +16,7 @@ The anchor document is highlighted in blue.
 
 
 [role="screenshot"]
-image::images/Discover-ContextView.png[Context View]
+image::images/Discover-ContextView.png[Image showing context view feature, with anchor documents highlighted in blue]
 
 [float]
 [[filter-context]]

docs/discover/document-data.asciidoc

@@ -44,7 +44,7 @@ immediately before and after your event.
 share the link for direct access to a particular document.
 
 [role="screenshot"]
-image::images/Expanded-Document.png[]
+image::images/Expanded-Document.png[Image showing expanded view, with JSON and table viewing options]
 
 
 [float]

docs/discover/field-filter.asciidoc

@@ -19,7 +19,7 @@ the field, the top 5 values for the field, and the percentage of documents
 that contain each value.
 +
 [role="screenshot"]
-image::images/filter-field.png[height=317]
+image::images/filter-field.png[Picture showing top 5 values for each field, and correspnding percentage of documents that contain each value]
 
 . Use the image:images/PositiveFilter.jpg[Positive Filter] icon to
 show only documents that contain that value,

docs/discover/search.asciidoc

@@ -28,7 +28,7 @@ configure a refresh interval to periodically resubmit your searches to
 retrieve the latest results.
 
 [role="screenshot"]
-image::images/autorefresh-interval.png[]
+image::images/autorefresh-interval.png[Image showing what refresh interval option looks like. The configurable time interval is located in the dropdown]
 
 You can also manually refresh the search results by
 clicking the *Refresh* button.

docs/discover/set-time-filter.asciidoc

@@ -14,7 +14,7 @@ range in the histogram.
 Use the time filter to change the time range. By default, the time filter is set
 to the last 15 minutes.
 
-. Click image:images/time-filter-calendar.png[].
+. Click image:images/time-filter-calendar.png[Calendar icon].
 
 . Choose one of the following:
 
@@ -53,4 +53,4 @@ when you hover over a valid start point.
 * Click the dropdown, then select an interval.
 
 [role="screenshot"]
-image::images/Histogram-Time.png[Time range selector in Histogram]
+image::images/Histogram-Time.png[Time range selector in Histogram dropdown]