[DO-1600] Add NetworkPolicy Mermaid (!35)

[DO-1600]

Co-authored-by: denis.patrakeev <denis.patrakeev@avroid.tech>
Reviewed-on: https://git.avroid.tech/K8s/k8s-configs/pulls/35

clusters/k8s-avroid-office.prod.local/namespaces/prod/mermaid/argocd-apps-plantuml-network-policy.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: mermaid-in
+  namespace: prod
+  labels:
+    app.kubernetes.io/managed-by: argocd
+spec:
+  podSelector:
+    matchLabels:
+      app.kubernetes.io/name: mermaid
+  policyTypes:
+    - Ingress
+  ingress:
+    - from:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: ingress-nginx