[5.x] [docs] Add documentation for the context view (#11382)

Backports PR #11222

Add documentation for the context view

fixes #11216

docs/discover.asciidoc

@@ -20,4 +20,6 @@ include::discover/field-filter.asciidoc[]
 
 include::discover/document-data.asciidoc[]
 
+include::discover/context.asciidoc[]
+
 include::discover/viewing-field-stats.asciidoc[]

docs/discover/context.asciidoc

@@ -0,0 +1,47 @@
+[[document-context]]
+== Viewing Document Context
+
+For certain applications it can be useful to inspect a window of documents 
+surrounding a specific event. The context view enables you to do just that for
+index patterns that are configured to contain time-based events.
+
+To show the context surrounding an anchor document, click the *Expand* button 
+image:images/ExpandButton.jpg[Expand Button] to the left of the document's 
+table entry and then click the *View surrounding documents* link.
+
+image::images/Expanded-Document.png[Expanded Document]
+{nbsp}
+
+The context view displays a number of documents before and after the anchor 
+document. The anchor document itself is highlighted in blue. The view is sorted 
+by the time field specified in the index pattern configuration and uses the 
+same set of columns as the Discover view the context was opened from.
+
+image::images/Discover-ContextView.png[Context View]
+
+NOTE: The number of documents displayed by default can be configured 
+via the `context:defaultSize` setting in <<advanced-options, *Management > 
+Advanced Options*>>.
+
+=== Changing the Context Size
+
+You can change the number documents displayed before and after the anchor 
+document independently.
+
+To increase the number of displayed documents that are newer than the anchor
+document, click the *Load 5 more* button above the document list or enter the 
+desired number into the input box right of the button.
+
+image::images/Discover-ContextView-SizePicker-Newer.png[]
+{nbsp}
+
+To increase the number of displayed documents that are older than the anchor
+document, click the *Load 5 more* button below the document list or enter the 
+desired number into the input box right of the button.
+
+image::images/Discover-ContextView-SizePicker-Older.png[]
+{nbsp}
+
+NOTE: The default number of documents loaded with each button click can be
+configured via the `context:step` setting in <<advanced-options, *Management >
+Advanced Options*>>.

docs/discover/document-data.asciidoc

@@ -18,8 +18,9 @@ image::images/Expanded-Document.png[]
 
 To view the original JSON document (pretty-printed), click the *JSON* tab.
 
-To view the document data as a separate page, click the document link. You can
-bookmark and share this link to provide direct access to a particular document.
+To view the document data as a separate page, click the *View single document* 
+link. You can bookmark and share this link to provide direct access to a 
+particular document.
 
 To display or hide a field's column in the Documents table, click the
 image:images/add-column-button.png[Add Column] *Toggle column in table* button.