docs: Replace memcached-operator in v1.39.0 update instructions (#6898)

Signed-off-by: Mario Kahlhofer <[email protected]>

Author: blu3r4y

Diff for: website/content/en/docs/upgrading-sdk-version/v1.39.0.md

@@ -72,7 +72,7 @@ so this release should be easier to follow.
     + kind: NetworkPolicy
     + metadata:
     +   labels:
-    +     app.kubernetes.io/name: memcached-operator
+    +     app.kubernetes.io/name: <operator-name>
     +     app.kubernetes.io/managed-by: kustomize
     +   name: allow-metrics-traffic
     +   namespace: system
@@ -107,7 +107,7 @@ so this release should be easier to follow.
     + kind: NetworkPolicy
     + metadata:
     +   labels:
-    +     app.kubernetes.io/name: memcached-operator
+    +     app.kubernetes.io/name: <operator-name>
     +     app.kubernetes.io/managed-by: kustomize
     +   name: allow-webhook-traffic
     +   namespace: system