docs: you can block a user without reporting them

[allendorf]

Change was merged a few weeks ago but forgot to update the docs.

---

Note

Low Risk
Documentation-only change with no runtime, security, or data-handling impact.

Overview
Updates Hub moderation docs to match shipped behavior: users can block someone from a discussion comment without filing a report.

The Reporting a comment section now notes that blocking can happen during a report or on its own via the comment menu. Blocking a user is rewritten as two paths—block while reporting through the modal, or use Block @username from another user’s comment menu (with confirmation).

^{Reviewed by Cursor Bugbot for commit 8483fbc. Bugbot is set up for automated code reviews on this repo. Configure here.}

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.