[doc] update repository docs

borrowing some of @notplant's wording in the README:
 https://git.coopcloud.tech/coop-cloud/mumble/pulls/1/files

MAINTENANCE and PULL_REQUEST_TEMPLATE are copied from traefik as per
 https://docs.coopcloud.tech/maintainers/maintain/#templates
with modifications to allow for single maintainers

README.md

@@ -21,14 +21,36 @@ Low latency, high quality voice chat application.
 ## Basic usage
 
 1. Set up Docker Swarm and [`abra`]
-2. Deploy [`coop-cloud/traefik`]
-3. `abra app new ${REPO_NAME} --secrets` (optionally with `--pass` if you'd like
-   to save secrets in `pass`)
-4. `abra app config YOURAPPDOMAIN` - be sure to change `$DOMAIN` to something that resolves to
-   your Docker swarm box
-5. `abra app deploy YOURAPPDOMAIN`
-6. Open the configured domain in your browser to finish set-up
+2. Configure [`coop-cloud/traefik`] to accept mumble's ports:
+    ```bash
+    $ abra app config <YOURTRAEFIKDOMAIN>
+    ```
+  - uncomment lines related to mumble:
+    ```
+    COMPOSE_FILE="$COMPOSE_FILE:compose.mumble.yml"
+    MUMBLE_ENABLED=1
+    ```
+  - save the config and deploy traefik:
+    ```bash
+    $ abra app deploy <YOURTRAEFIKCOMAIN> --force
+    ```
+3. `abra app new mumble`
+4. `abra app config <YOURAPPDOMAIN>`
+5. `abra app deploy <YOURAPPDOMAIN>`
+6. Connect with a [Mumble client] to port 64738 on your domain
+
+## Web Client
+
+An optional browser-based client is available via the `compose.mumbleweb.yml`
+overlay. To enable it:
+1. `abra app config mumble.example.com` — uncomment the line:
+   ```
+   COMPOSE_FILE="$COMPOSE_FILE:compose.mumbleweb.yml"
+   ```
+2. `abra app deploy <YOURAPPDOMAIN> --force`
+3. Open `https://<YOURAPPDOMAIN>` in a browser
 
 [`abra`]: https://git.coopcloud.tech/coop-cloud/abra
 [`coop-cloud/traefik`]: https://git.coopcloud.tech/coop-cloud/traefik
 coop-cloud/traefik
+[Mumble client]:(https://www.mumble.info/downloads/)