docs: fix releasing section wrong heading style

CONTRIBUTING.md

@@ -121,7 +121,7 @@ Adminterface hosts release candidate builds on Github packages. If you wish to t
    yarn upgrade @cmdbrew/adminterface@[VERSION]
    ```
 
-### Releasing (maintainers only)
+## Releasing (maintainers only)
 We use Github Actions to publish releases based on the git tags automatically. See [`.github/workflows/release.yml`](https://github.com/CMDBrew/adminterface/.github/workflows/release.yml) for more information.
 1. Update Gem version in [`lib/adminterface/version.rb`](https://github.com/CMDBrew/adminterface/lib/adminterface/version.rb)
 2. Update NPM package version in [`package.json`](https://github.com/CMDBrew/adminterface/package.json)