Link to Gitea docs on index page (#323)

Based on social media feedback regarding Forgejo's documentation
not always covering everything. Although it is probably best to use
the Forgejo documentation wherever possible, it is probably in the
interest of our users to link back to both sites.

Reviewed-on: https://codeberg.org/Codeberg/Documentation/pulls/323

content/home.md

@@ -16,6 +16,7 @@ Codeberg's Documentation mostly includes tutorials specific to using the platfor
 If what you are trying to do is not covered by our Documentation, the following resources can be helpful:
 
 - [Forgejo User Guide](https://forgejo.org/docs/latest/user/)
+- [Gitea Usage Guide](https://docs.gitea.com/category/usage)
 - [Woodpecker CI Documentation](https://woodpecker-ci.org/docs/intro)
 - [Weblate Documentation](https://docs.weblate.org/en/latest/index.html)