Add reference content, and move Lens docs to their own page

docs/redirects.asciidoc

@@ -96,11 +96,6 @@ More information on this new feature is available in <<apm-alerts>>.
 
 This content has moved to the <<development-rbac, Security>> page.
 
-[role="exclude",id="TSVB"]	
-== TSVB	
-
-This page was deleted. See <<tsvb-advanced-editor>>.
-
 [role="exclude",id="managing-cross-cluster-replication"]
 == Cross-Cluster Replication
 
@@ -203,3 +198,6 @@ This page has moved. Refer to <<url-template-variables>>.
 == Visualize
 
 This content has moved. See <<dashboard, **Dashboard**>>.
+
+[role="exclude",id="explore-dashboard-data"]
+This content has moved. See <<dashboard, **Dashboard**>>.

docs/user/dashboard/advanced-editors.asciidoc

@@ -20,19 +20,18 @@ image::images/tsvb.png[TSVB UI]
 
 [float]
 [[vega-advanced-editor]]
-=== Vega
+=== Custom visualizations
 
-*Vega* and *Vega-Lite* provide the grammar language, using a JSON-based syntax, for building custom panels.
+*Vega* and *Vega-Lite* are visualization grammars that are integrated into {kib} for custom visualizations.
 
-* *Vega* — A powerful and feature-rich grammar language.
+* *Vega-Lite* — A high-level grammar for rapid analysis
 
-* *Vega-Lite* — A simplified and easier to use grammar language.
+* *Vega* — A declarative language with support for interactivity
 
 *Vega* and *Vega-Lite* panels can display one or more data sources, including {es}, Elastic Map Service,
-URL, or static data, and support <<reference-for-kibana-extensions,{kib} extensions>> that allow you to embed the panels on your dashboard and add interactive tools. With *Vega* and *Vega-Lite*, the types of 
-panels you can create are endless.
+URL, or static data, and support <<reference-for-kibana-extensions,{kib} extensions>> that allow you to embed the panels on your dashboard and add interactive tools.
 
-Use *Vega* and *Vega-Lite* when you want to create visualizations with:
+Use *Vega* or *Vega-Lite* when you want to create visualizations with:
 
 * Aggregations that use `nested` or `parent/child` mapping
 * Aggregations without an index pattern
@@ -42,6 +41,8 @@ Use *Vega* and *Vega-Lite* when you want to create visualizations with:
 * Scatter charts, sankey charts, and custom maps
 * An unsupported visual theme
 
+These grammars have some limitations: they do not support tables, and can't run queries conditionally.
+
 image::images/vega.png[Vega UI]
 
 For detailed *Vega* and *Vega-Lite* information and examples, refer to <<resources-and-examples,Resources and examples>>. 
@@ -50,18 +51,15 @@ For detailed *Vega* and *Vega-Lite* information and examples, refer to <<resourc
 [[timelion-advanced-editor]]
 === Timelion
 
-*Timelion* is a time series data visualizer that enables you to combine independent data sources within a single visualization.
-On *Timelion* visualizations, your data is displayed along a scale that changes color according to where your data falls on the specified scale. 
-Use the gauge to show how metric values relate to reference threshold values, or determine how a specified field is performing versus how it is expected to perform.
-
 *Timelion* is driven by a simple expression language that you use to:
 
-* Retrieve time series data
-* Perform calculations to find the answers to complex questions
+* Retrieve time series data from one or more indices
+* Perform math across two or more time series
 * Visualize the results
 
-image:images/gauge.png[Gauge]
+image:dashboard/images/timelion.png[Timelion]
 
 include::tsvb.asciidoc[]
 include::vega.asciidoc[]
+include::vega-reference.asciidoc[]
 include::timelion.asciidoc[]

docs/user/dashboard/aggregation-based.asciidoc

@@ -1,7 +1,26 @@
 [[add-aggregation-based-visualization-panels]]
 == Create aggregation-based visualization panels
 
-Aggregation-based visualization panels allow you to visualize aggregated data from a <<save-open-search,saved search>> or <<index-patterns, index pattern>>. 
+Aggregation-based visualizations are the core {kib} panels, and are not optimized
+for a specific use case. If you are new to {kib}, <<create-panels-with-lens,Lens>> is recommended as a
+simpler way to get started.
+
+The main features that these panel types have compared to other {kib} panel types are:
+
+* Support for heat map, tag cloud, gauge, and goal chart types
+* Support for split charts at up to 3 levels of aggregation, more than *Lens* and *TSVB*
+* Time series data is not required
+* Ability to use a <<save-open-search,saved search>> as an input
+* Data table can be sorted, also supports summary row and percentage column features
+* Can assign specific colors to series
+* Ability for plugin authors to extend the features
+
+These panel types also have some limitations:
+
+* Not as simple as *Lens*
+* Limited styling options
+* No support for math
+* No support for multiple indices
 
 [float]
 [[types-of-visualization-panels]]
@@ -21,7 +40,7 @@ Use area charts to compare two or more categories over time, and display the mag
 
 a| *Data table*
 
-Displays your raw data or aggregation results in a tabular format. Use data tables to display server configuration details, track counts, min,
+Displays your aggregation results in a tabular format. Use data tables to display server configuration details, track counts, min,
 or max values for a specific field, and monitor the status of key services.
 
 | image:images/data_table.png[Data table]
@@ -99,7 +118,7 @@ Choose the type of panel you want to create, then use the editor to configure th
 
 . From the editor, add the <<aggregation-reference,aggregations>> you want to visualize, then click *Update*. 
 +
-NOTE: To use *auto* from the *Minimal interval* dropdown, the *Date Histogram* aggregation must be the primary field. 
+NOTE: For the *Date Histogram* to use an *auto interval*, the date field must match the primary time field of the index pattern.
 
 . To change the order, drag the aggregations along the editor. 
 +