[8.x] [Serverless][8.18] EQL Sequence alert suppression (backport #6291)

[mergify]

Fixes #5886

ESS

• Alert suppression - Made the following changes:
  • Removed the second bullet in the requirements note at the start of the page since alert suppression for EQL rules will be GA in 8.18.
  • Updated the note after step 1 that explains how suppression fields with multiple values are handled. Added a third bullet for event correlation rules using sequence queries.
• Create a detection rule | Create an event correlation rule - Removes the tech preview label from step 6, which lets users know that they can suppress alerts from this rule type.

Serverless

NOTE: Suppression for EQL rules in Serverless will go GA around the same time that 8.18 GAs. I'll open a separate PR to update the Serverless docs once that date approaches.

• Alert suppression - Same changes as described above

---

This is an automatic backport of pull request #6291 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of ed389ce has failed:

On branch mergify/bp/8.x/pr-6291
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit ed389cef.
  (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/alert-suppression.asciidoc
	modified:   docs/detections/rules-ui-create.asciidoc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/serverless/alerts/alert-suppression.asciidoc

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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