docs: ✏️ add "Explore underlying data" user docs

docs/drilldowns/explore-underlying-data.asciidoc

@@ -0,0 +1,41 @@
+[[explore-underlying-data]]
+== Explore the underlying data for a visualization
+
+++++
+<titleabbrev>Explore the underlying data</titleabbrev>
+++++
+
+Dashboard panels have an *Explore underlying data* action that navigates you to *Discover*,
+where you can narrow your documents to the ones you'll most likely use in a  visualization.
+This action is available for visualizations backed by a single index pattern.
+
+You can access *Explore underlying data* in two ways: from the panel context
+menu or from the menu that appears when you interact with the chart.
+
+[float]
+[[explore-data-from-panel-context-menu]]
+=== Explore data from panel context menu
+
+The *Explore underlying data* action in the panel menu navigates you to Discover,
+carrying over the index pattern, filters, query, and time range for the visualization.
+
+[role="screenshot"]
+image::images/explore_data_context_menu.png[Explore underlying data from panel context menu]
+
+[float]
+[[explore-data-from-chart]]
+=== Explore data from chart action
+
+Initiating *Explore underlying data* from the chart also navigates to Discover,
+carrying over the current context for the visualization. In addition, this action
+applies the filters and time range created by the events that triggered the action.
+
+[role="screenshot"]
+image::images/explore_data_in_chart.png[Explore underlying data from chart]
+
+You can disable this action by adding the following line to your `kibana.yml` config.
+
+["source","yml"]
+-----------
+xpack.discoverEnhanced.actions.exploreDataInChart.enabled: false
+-----------

docs/user/dashboard.asciidoc

@@ -160,6 +160,7 @@ When you're finished adding and arranging the panels, save the dashboard.
 . Enter the dashboard *Title* and optional *Description*, then *Save* the dashboard.
 
 include::{kib-repo-dir}/drilldowns/drilldowns.asciidoc[]
+include::{kib-repo-dir}/drilldowns/explore-underlying-data.asciidoc[]
 
 [[sharing-dashboards]]
 == Share the dashboard