Update Query History readme with latest feature additions (#7529)

extensions/query-history/README.md

@@ -4,7 +4,7 @@ Adds a Query History panel for viewing and running past executed queries.
 
 ### How do I view the history?
 
-Query History is displayed as a tab in the tab panel, which is toggled by the *View: Toggle Panel* command.
+Query History is displayed as a tab in the tab panel, which is toggled by the **View: Toggle Panel** command.
 
 ![Query History tab](https://raw.githubusercontent.com/microsoft/azuredatastudio/master/extensions/query-history/images/QueryHistoryTab.PNG)
 
@@ -34,7 +34,24 @@ This will do the same thing as Open Query but will additionally run the statemen
 
 #### Delete
 
-This will permanently delete the row from the view.
+This will permanently delete the selected history row.
+
+#### Clear All History
+
+This will permanently delete **ALL** history rows.
+
+This action is also available from the command palette (**Query History: Clear All History**) and as an action button on the panel.
+
+#### Pause/Start Query History Capture
+
+This will Pause or Start Query History Capture. While paused no data will be stored for queries run.
+
+This action is also available from the command palette (**Query History: Toggle Query History Capture**) and as an action button
+on the panel.
+
+### Data Storage
+
+Currently all information is stored in-memory and not persisted upon application exit.
 
 ## Code of Conduct
 This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.