docs: update skills repository URLs to OpenHands/extensions

[neubig]

Summary

Update all documentation references from OpenHands/skills to OpenHands/extensions to support the repository rename.

Changes

File	Change
overview/skills.mdx	Main skills overview page
overview/skills/public.mdx	Global skills documentation (multiple URLs)
overview/skills/keyword.mdx	Keyword-triggered skills docs
overview/skills/repo.mdx	Repository skills docs
sdk/guides/skill.mdx	SDK skills guide
sdk/guides/github-workflows/pr-review.mdx	PR review workflow docs
openhands/usage/use-cases/code-review.mdx	Code review use case docs

Merge Order

This PR can be merged at any time after the skills repository is renamed to OpenHands/extensions.

• Before rename: Links to OpenHands/extensions will be broken
• After rename: All links will work correctly; GitHub redirects will also work for old URLs

Related PRs

This is part of a coordinated refactoring:

Repository	PR	Status	Merge Order
OpenHands/skills	#50	Open	1️⃣ Merge first
GitHub Settings	(manual)	Pending	2️⃣ Rename skills → extensions
OpenHands/software-agent-sdk	#2085	Open	3️⃣ Merge after rename
OpenHands/docs	This PR	Open	3️⃣ Merge after rename

Testing

All links will work correctly once the repository is renamed. GitHub's automatic redirects will handle any edge cases during the transition period.

@neubig can click here to continue refining the PR

[openhands-ai]

Looks like there are a few issues preventing this PR from being merged!

• GitHub Actions are failing:
  • .github/workflows/sync-agent-sdk-openapi.yml
  • .github/workflows/sync-docs-code-blocks.yml

If you'd like me to help, just leave a comment, like

@OpenHands please fix the failing actions on PR #337 at branch `refactor/extensions-rename`

Feel free to include any additional details that might help me get this PR into a better state.

_{^{You can manage your notification settings}}

[all-hands-bot]

🟢 Good taste - Clean, mechanical URL update that solves a real problem without over-engineering.

Linus-Style Analysis:
✅ Solves actual problem (repo rename)
✅ Simplest possible solution (find/replace)
✅ Zero breaking changes
✅ Comprehensive coverage across all docs

Verdict: ✅ Worth merging

Key Insight: This is exactly what a documentation update should be - boring, mechanical, and correct.

[all-hands-bot]

🟢 Good taste - Clean, mechanical URL update. No issues found. LGTM.