chart: bind the HTTPRoute to a named gateway listener

The route carried no sectionName, so it attached to every listener whose
hostname matched — including the hostname-less plaintext HTTP listener.
On a publicly reachable hostname that means the API accepts bearer tokens
over cleartext.

networking.listener names the listener to bind to. It defaults to empty,
which keeps the previous attach-to-all behaviour.

Also document the Kubernetes install path, which the README omitted.

README.md

@@ -50,6 +50,31 @@ docker run -p 8080:8080 -v $(pwd)/data:/data \
   terdut-server
 ```
 
+### Kubernetes
+
+A Helm chart is published from this repository:
+
+```bash
+helm repo add terdut-server https://yeniklas.github.io/terdut-server
+helm upgrade --install terdut-server terdut-server/terdut-server \
+  --namespace terdut-server --create-namespace \
+  --set networking.hostname=terdut.example.com
+```
+
+The chart expects a [Gateway API](https://gateway-api.sigs.k8s.io/) Gateway named `envoy-main` in
+the `envoy-gateway-system` namespace to already exist — it renders an `HTTPRoute` against it rather
+than an `Ingress`. TLS is terminated at the gateway, so the server itself never sees a certificate.
+
+| Value | Default | Description |
+|---|---|---|
+| `networking.hostname` | `terdut.example.com` | Hostname the `HTTPRoute` serves |
+| `networking.listener` | `""` | Gateway listener (`sectionName`) to bind to. Empty attaches to every matching listener, **including plaintext HTTP** — set it to the HTTPS listener's name to serve TLS only |
+| `networking.servicePort` | `8080` | Port the route forwards to; keep in sync with `service.port` |
+| `bootstrap.enabled` | `true` | Runs a post-install hook that creates the first user and stores its API key in the `<release>-admin-key` Secret. Already-bootstrapped servers are left alone |
+
+The API key travels in an `Authorization: Bearer` header, so set `networking.listener` whenever the
+hostname is reachable outside a trusted network.
+
 ---
 
 ## Configuration