Add reference grant to allow monitoring services

Author: jb3

kubernetes/namespaces/nginx-gateway/reference-grants.yaml

@@ -0,0 +1,13 @@
+apiVersion: gateway.networking.k8s.io/v1beta1
+kind: ReferenceGrant
+metadata:
+  name: allow-nginx-gateway-to-monitoring
+  namespace: monitoring
+spec:
+  from:
+  - group: gateway.networking.k8s.io
+    kind: HTTPRoute
+    namespace: nginx-gateway
+  to:
+  - group: ""
+    kind: Service