fix(docker): let SELinux hosts read the bind-mounted checkout (#1391)

Allow the Docker checkout bind mount on SELinux hosts.

Contribution by @anilguvenc.

README.md

@@ -207,6 +207,8 @@ env UID=1026 GID=100 docker compose up -d
 
 Keep the `env`: bash treats `UID` as read-only, so a plain `UID=1026` in front of a command is silently ignored. If the container can't write the checkout, it says so at start. Docker Desktop on macOS and Windows maps ownership for you.
 
+On SELinux hosts (Fedora, RHEL), compose mounts the checkout with `:z` so the container may read it; Docker may relabel the checkout for container access, which can take a moment on a large checkout. Without that, the start fails with `Cannot find module '/app/scripts/docker-start.mjs'`.
+
 Behind a reverse proxy, put your keys in `.env` or pass them as environment variables - Provider Settings refuses proxied requests on purpose - and add the hostname you serve it on, for example `GEV_ALLOWED_HOSTS=globe.example.lan` (see [Sharing an instance](#-sharing-an-instance)).
 
 </details>