Update cost_details.md

Updating the cost details page to reflect the new historical costs feature.

content/en/account_management/plan_and_usage/cost_details.md

@@ -30,10 +30,11 @@
 ## Cost summary
 
 Use the cost summary to:
-- View estimated month-to-date costs
-- View projected end-of-month costs
-- View cost trends within the month
+- View estimated month-to-date and projected end-of-month costs
+- View historical costs
 - Filter and group costs by product or sub-organization
+- View month-over-month % and $ cost changes
+- View cost trends within the month
 - View cumulative day-over-day costs
 
 ### Projected Costs (parent organization)
@@ -42,17 +43,21 @@
 
 ### Cost Summary (parent organization)
 
-The cost summary functionality changes according to your Datadog usage as a single organization or a multi-organization. As a multi-organization, you can view estimated and projected costs for the parent organization and each sub-organization. 
+The cost summary functionality changes according to your Datadog usage as a single organization or a multi-organization. As a multi-organization, you can view estimated, projected and historical costs for the parent organization and each sub-organization. 
+
+{{< img src="static/images/account_management/plan_and_usage/multiorg-current-month-historical-costs.png" alt="Screenshot of the current month's Cost Summary for a parent organization, showing the overall month to date cost, projected cost, a graph with cumulative cost breakdowns, and a summary table including month-over-month cost changes." >}}
+
+View historical costs by toggling to previous months.
 
-{{< img src="account_management/plan_and_usage/multi-org-estimated-projected-cost-summary.png" alt="Screenshot of the Cost Summary for a parent organization, showing the overall month to date cost, projected cost, a graph of cumulative cost breakdown, and a summary table." >}}
+{{< img src="static/images/account_management/plan_and_usage/multiorg-prior-month-historical-costs.png" alt="Screenshot of a previous month's Cost Summary for a parent organization, showing the overall cost for the month, a graph with cumulative cost breakdowns, and a summary table including month-over-month cost changes." >}}
 
 1. While logged in to the parent organization, navigate to [Plan & Usage][2].
 1. Click the **Usage** tab.
 1. For a multi-organization, ensure the **Overall** tab is selected.
 
 #### View and filter
 
-Use the search facets at the left to filter the cost by **Products** or by **Sub-Orgs**. Use the **Over Time** tab to see how the cumulative day-over-day costs have changed.
+Use the search facets at the left to filter the cost by **Products** or by **Sub-Orgs**. Use the **Daily Cost** tab to see how the cumulative day-over-day costs have changed within the current month.
 
 #### Download
 
@@ -69,15 +74,15 @@
 
 As a sub-organization, you can view the costs for your organization only. This restriction allows for more distributed ownership and removes the need to grant broader Admin permissions to the parent organization.
 
-{{< img src="account_management/plan_and_usage/sub-org-estimated-projected-cost-summary.png" alt="Screenshot of the Cost Summary for a sub-organization, showing the overall month to date cost, projected cost, a graph of cumulative cost breakdown, and a summary table." >}}
+{{< img src="static/images/account_management/plan_and_usage/suborg-cost-trends.png" alt="Screenshot of the current month's Cost Summary for a sub-organization, showing the overall month to date cost, projected cost, a graph with cumulative cost breakdowns, and a summary table including month-over-month cost changes.">}}
 
 1. While logged in to the sub-organization, navigate to [Plan & Usage][2].
 1. Click the **Usage** tab.
 1. Ensure the **Overall** tab is selected.
 
 #### View and filter
 
-Use the search facets at the left to filter the cost by **Products**. Use the **Over Time** tab to see how the cumulative day-over-day costs have changed.
+Use the search facets at the left to filter the cost by **Products**. Use the **Daily Cost** tab to see how the cumulative day-over-day costs have changed within the current month.
 
 #### Download