Port PR 4488 to Serverless - adding k8s-otel quickstart guide

[eedugon]

Description

Porting #4488 to Serveless
Added a fix in stateful get-started main doc on the quickstarts section (missing links to the recently created quickstart guides).

Documentation sets edited in this PR

Check all that apply.

• Stateful (docs/en/observability/*)
• Serverless (docs/en/serverless/*)
• Integrations Developer Guide (docs/en/integrations/*)
• None of the above

Related issue

Closes #4535

Checklist

• Product/Engineering Review
• Writer Review

Follow-up tasks

Select one.

• This PR does not need to be ported to another doc set because:
  • The concepts in this PR only apply to one doc set (serverless or stateful)
  • The PR contains edits to both doc sets (serverless and stateful)
• This PR needs to be ported to another doc set:
  • Port to stateful docs: <link to PR or tracking issue>
  • Port to serverless docs: <link to PR or tracking issue>

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[mergify]

This pull request does not have a backport label. Could you fix it @eedugon? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-/d./d is the label to automatically backport to the /d./d branch. /d is the digit
  NOTE: backport-skip has been added to this pull request.

[dedemorton]

Just a couple minor edits to make this consistent with #4582.

Also make sure that you update the getting started overview here to include the link to the new quickstart: https://observability-docs_bk_4582.docs-preview.app.elstc.co/guide/en/observability/master/observability-get-started.html#quickstarts-overview

[eedugon]

Also make sure that you update the getting started overview here to include the link to the new quickstart:

Good catch @dedemorton , I had forgotten it even for the stateful docs, and I've seen that @alaudazzi had also forgotten it when adding the firehose quickstart in stateful. So I've updated the file observability-get-started.asciidoc in both doc sets (serverless and stateful).

[eedugon]

As now this PR touches a stateful file I'm adding backport labels.
cc: @dedemorton and @alaudazzi

[alaudazzi]

Have we agreed to remove the images in the Collect your data section?

[eedugon]

@alaudazzi ,

Have we agreed to remove the images in the Collect your data section?

No, we haven't, we've decided to keep them as we can always remove them instead of updating if they end up being outdated too fast.

Take a look at @dedemorton's comment #4582 (comment)

Also PR 4582 is already merged and the updated screenshot in firehose quickstart is live :)

[alaudazzi]

I left a few minor editing suggestions, otherwise LGTM.

[eedugon]

This requires a final review as after changing a new file the merge is not possible (cc: @dedemorton ) :)