Add section about AI connector to serverless

[dedemorton]

Ports https://github.com/elastic/observability-docs/pull/3906 to serverless.

[github-actions[bot]]

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[mergify[bot]]

This pull request does not have a backport label. Could you fix it @dedemorton? 🙏 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.

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[mergify[bot]]

This pull request is now in conflict. Could you fix it @dedemorton? 🙏 To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b port#3906_serverless upstream/port#3906_serverless
git merge upstream/main
git push upstream port#3906_serverless