gateway-api: typo

Signed-off-by: Maël Valais <[email protected]>

content/docs/usage/gateway.md

@@ -73,7 +73,7 @@ The corresponding Helm command is:
 ```sh
 helm upgrade --install cert-manager jetstack/cert-manager --namespace cert-manager \
   --set apiVersion="controller.config.cert-manager.io/v1alpha1" \
-  --set config.kind=ControllerConfiguration" \
+  --set config.kind="ControllerConfiguration" \
   --set config.enableGatewayAPI=true
 ```