fix: update Docker registry authentication for Gitea

- Use GITEA_TOKEN or github.token for authentication
- Add documentation for manual token setup if needed

.github/workflows/release-server.yaml

@@ -123,7 +123,7 @@ jobs:
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
+          password: ${{ secrets.GITEA_TOKEN || github.token }}
 
       - name: docker metadata
         id: docker_meta