fix(docs): update invalid hash links in PR and moderator handbooks

[soumbra]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Closes #1365

This PR resolves the Starlight link validation errors (invalid hash) that occur during the local docs build.

Specifically, it fixes the invalid markdown hash links in:

• how-to-open-a-pull-request.mdx (updated to point to #set-up-syncing-from-parent which matches the actual heading in the local setup guide).
• moderator-handbook.mdx (updated to point to #where-can-i-get-help-if-im-stuck-on-something-not-covered-here matching the real FAQ section heading).

Built the docs site locally on Fedora 43 / Chrome and verified that the invalid hash errors for these specific files are no longer present in the Starlight output.

[soumbra]

Hi @majestic-owl448, suggestion applied, thank you!

I saw that you marked the comment about the 8 links as outdated, but just to clarify: the other 6 errors in the log are just warnings about local links (localhost ports). I only corrected the 2 broken markdown hashes in this PR because I considered them more important at this time.

Let me know if everything looks good now!

[soumbra]

Hi @majestic-owl448, suggestion applied, thank you!

I saw that you marked the comment about the 8 links as outdated, but just to clarify: the other 6 errors in the log are just warnings about local links (localhost ports). I only corrected the 2 broken markdown hashes in this PR because I considered them more important at this time.

Let me know if everything looks good now!

[majestic-owl448]

Thank you for your contribution to the page! 👍
We are happy to accept these changes and look forward to future contributions. 🎉