[8.15] [TH: Investigations][Serverless & 8.15] New previews in expand…

…able flyout (backport #5605) (#5634)

* [TH: Investigations][Serverless & 8.15] New previews in expandable flyout (#5605)

* First draft

* Serverless updates

* Adds serverless changes

* Update entities screenshot

* Updated final screenshots

* Update docs/detections/alerts-view-details.asciidoc

Co-authored-by: Joe Peeples <[email protected]>

* Update docs/serverless/alerts/view-alert-details.mdx

Co-authored-by: Joe Peeples <[email protected]>

---------

Co-authored-by: Joe Peeples <[email protected]>
(cherry picked from commit 5d20347)

# Conflicts:
#	docs/serverless/alerts/view-alert-details.mdx
#	docs/serverless/images/view-alert-details/-detections-expanded-correlations-view.png
#	docs/serverless/images/view-alert-details/-detections-expanded-entities-view.png

* Delete docs/serverless directory and its contents

---------

Co-authored-by: Nastasha Solomon <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

docs/detections/alerts-view-details.asciidoc

@@ -52,7 +52,7 @@ IMPORTANT: If you've enabled grouping on the Alerts page, the alert details flyo
 [[preview-panel]]
 === Preview panel 
 
-The preview panel shows more information about the rule associated with the alert and the reason the alert was generated. This panel overlays the right panel when you click **Show rule details** or **Show full reason** in the <<about-section,About>> section. To close the preview panel, click **x**. 
+Some areas in the flyout provide previews when you click on them. For example, clicking **Show rule summary** in the rule description displays a preview of the rule's details. To close the preview, click **x**. 
 
 [role="screenshot"]
 image::images/alert-details-flyout-preview-panel.gif[Preview panel of the alert details flyout, 65%]
@@ -86,7 +86,7 @@ image::images/about-section-rp.png[About section of the Overview tab, 65%]
 
 The About section has the following information:
 
-* **Rule description**: Describes the rule's purpose or detection goals. Click **Show rule summary** to display more details about the rule within the <<preview-panel,preview panel>>. From the preview panel, click **Show rule details** to view the rule's details page. 
+* **Rule description**: Describes the rule's purpose or detection goals. Click **Show rule summary** to display a preview of the rule's details. From the preview, click **Show rule details** to view the rule's details page. 
 
 * **Alert reason**: Describes the source event that generated the alert. Event details are displayed in plain text and ordered logically to provide context for the alert. Click **Show full reason** to display the alert reason in the event rendered format within the <<preview-panel,preview panel>>.  
 +