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

[mergify]

Fixes #5495

Previews:

• 8.15 - Revised the preview panel description, updated entity and correlation screenshots, and made minor updates elsewhere.
• Serverless - Same changes

  ---

  This is an automatic backport of pull request [TH: Investigations][Serverless & 8.15] New previews in expandable flyout #5605 done by Mergify.

[mergify]

Cherry-pick of 5d20347 has failed:

On branch mergify/bp/8.15/pr-5605
Your branch is up to date with 'origin/8.15'.

You are currently cherry-picking commit 5d203473.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   docs/detections/alerts-view-details.asciidoc
	modified:   docs/detections/images/expanded-correlations-view.png
	modified:   docs/detections/images/expanded-entities-view.png

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/serverless/alerts/view-alert-details.mdx
	deleted by us:   docs/serverless/images/view-alert-details/-detections-expanded-correlations-view.png
	deleted by us:   docs/serverless/images/view-alert-details/-detections-expanded-entities-view.png

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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