[8.4] [DOCS] Removes frozen indices limitation item from anomaly detection docs (backport #2828)

[mergify]

Overview

This PR removes a anomaly detection limitation item about frozen indices that no longer applies from docs.

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This is an automatic backport of pull request #2828 done by Mergify.

[mergify]

Cherry-pick of 04632d2 has failed:

On branch mergify/bp/8.4/pr-2828
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You are currently cherry-picking commit 04632d2f.
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Unmerged paths:
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	both modified:   docs/en/stack/ml/anomaly-detection/ml-limitations.asciidoc

no changes added to commit (use "git add" and/or "git commit -a")

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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