Added DM and GM restriction note for quarntine message feature

[harshilsharma63]

Summary

Docs PR for complimenting mattermost/mattermost#37841

Ticket Link

Fixes https://mattermost.atlassian.net/browse/MM-70099

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: e3a23021-e4cd-4c16-954c-bd3a88fbfb48

📥 Commits

Reviewing files that changed from the base of the PR and between bb693ea and 78c81f0.

📒 Files selected for processing (1)

• source/end-user-guide/collaborate/flag-messages.rst

🚧 Files skipped from review as they are similar to previous changes (1)

• source/end-user-guide/collaborate/flag-messages.rst

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📝 Walkthrough

Walkthrough

The flag messages guide states that message quarantine is available in public and private channels, but not in direct or group messages.

Changes

Message quarantine documentation

Layer / File(s)	Summary
Document supported channel types source/end-user-guide/collaborate/flag-messages.rst	The guide identifies public and private channels as supported. It excludes direct and group messages.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the added documentation about direct and group message restrictions for message quarantine.
Description check	✅ Passed	The description identifies this as documentation for the quarantine message restrictions and links it to the related pull request and ticket.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch quarntine_post_dm_gm_doc

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_{Comment @coderabbitai help to get the list of available commands.}

[Copilot]

Pull request overview

Updates the end-user documentation for the Quarantine for Review feature to clarify where the action is available, aligning the docs with the related Mattermost product change.

Changes:

• Added a note stating that quarantining is available only for public/private channel messages (not DMs or GMs).

[github-actions]

Newest code from mattermost has been published to preview environment for Git SHA bb693ea

[github-actions]

Newest code from mattermost has been published to preview environment for Git SHA 78c81f0

[Combs7th]

@harshilsharma63 - Thank you for the doc update! Before merge, can you please add the corresponding server release milestone if applicable? Thanks!

[harshilsharma63]

@Combs7th done. Added to the v11.11 milestone.

[github-actions]

Newest code from mattermost has been published to preview environment for Git SHA e1f9937