The standalone `environment-to-ini` tool was removed in https://github.com/go-gitea/gitea/pull/35735 and its functionality is now built into the Gitea binary. This PR:
- Removes outdated links to the removed `contrib/environment-to-ini` directory
- Updates the "Use environment variables to setup Gitea" section in the config cheat sheet
- Adds examples showing how env vars map to `app.ini` settings and the `__FILE` suffix for secrets
*This PR was authored by Claude.*
Reviewed-on: https://gitea.com/gitea/docs/pulls/355
Reviewed-by: wxiaoguang <29147+wxiaoguang@noreply.gitea.com>
Reviewed-by: TheFox0x7 <95654+thefox0x7@noreply.gitea.com>
- Always use a relative markdown link so that we can jump even if we edit it in local env or read it in code hosting server.
Reviewed-on: https://gitea.com/gitea/docs/pulls/1
