Add md extension to relref

Co-authored-by: Alan Dooley <ADubhlaoich@users.noreply.github.com>

Author: kate-osborn

site/content/how-to/traffic-management/routing-traffic-to-your-app.md

@@ -132,7 +132,7 @@ spec:
 EOF
 ```
 
-This gateway is associated with the NGINX Gateway Fabric through the **gatewayClassName** field. The default installation of NGINX Gateway Fabric creates a GatewayClass with the name **nginx**. NGINX Gateway Fabric will only configure gateways with a **gatewayClassName** of **nginx** unless you change the name via the `--gatewayclass` [command-line flag]({{< relref "/reference/cli-help#static-mode" >}}).
+This gateway is associated with the NGINX Gateway Fabric through the **gatewayClassName** field. The default installation of NGINX Gateway Fabric creates a GatewayClass with the name **nginx**. NGINX Gateway Fabric will only configure gateways with a **gatewayClassName** of **nginx** unless you change the name via the `--gatewayclass` [command-line flag]({{< relref "/reference/cli-help.md#static-mode" >}}).
 
 We specify a [listener](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1.Listener) on the gateway to open an entry point on the cluster. In this case, since the coffee application accepts HTTP requests, we create an HTTP listener, named **http**, that listens on port 80.