Draft: GitLab Chat: Fix what is a fork url

What does this MR do and why?

Fix "what is a fork" url.

Screenshots or screen recordings

Url

How to set up and validate locally

1. Enable Tanuki Bot
   1. gdk update
   2. echo "Feature.enable(:openai_experimentation)" | rails c
   3. echo "Feature.enable(:tanki_bot)" | rails c
   4. echo "Feature.enable(:super_sidebar_nav)" | rails c
   5. gdk config set pgvector.enabled true
   6. gdk config set gitlab.rails.databases.embedding.enabled true
   7. gdk reconfigure
   8. (optional, if reconfigure fails) sudo ln -s /Library/Developer/CommandLineTools/SDKs/MacOSX13.3.sdk /Library/Developer/CommandLineTools/SDKs/MacOSX13.0.sdk && gdk reconfigure
   9. run script from gitlab-com/gl-infra/production#10588 (comment 1373586079)
2. Help > Ask GitLab Chat
3. Verify "what is a fork" link

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.