docs(netpol): make the paperless probe citation a resolvable path (REN-116)

`paperless-ns.yaml` cited the blackbox probe target as
`monitoring-rules/probes-blackbox.yaml:250`. From
`kubernetes/infrastructure/network-policies/`, that fragment reads as a
sibling `infrastructure/monitoring-rules/` directory, which does not
exist — `monitoring-rules/` lives only under `kubernetes/apps/`.

Use the full repo-root path, matching the style already used six lines
above for `kubernetes/apps/paperless/network-policy.yaml`. Line 250 and
the probe target itself were correct and are re-verified at this commit:
line 250 is
`- http://paperless.paperless.svc.cluster.local:80/accounts/login/`.

Comments only. Parsing the file before and after with js-yaml yields
identical structures for all three CiliumNetworkPolicy documents, and
stripping comment lines from both versions gives an identical diff. No
`spec` change, no new resource, nothing applied to the cluster.

Follow-up from the REN-110 review of PR #997 (merged as 0995e8d5).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

kubernetes/infrastructure/network-policies/paperless-ns.yaml

@@ -25,7 +25,8 @@ spec:
     # because both are load-bearing — CNPG reaches the postgres cluster
     # from `database`, and the blackbox probe of
     # http://paperless.paperless.svc.cluster.local:80/accounts/login/
-    # (monitoring-rules/probes-blackbox.yaml:250) runs from `monitoring`.
+    # (kubernetes/apps/monitoring-rules/probes-blackbox.yaml:250) runs
+    # from `monitoring`.
     # Scoping them to specific pods and ports is tracked in REN-28.
     - fromEndpoints:
         - matchLabels: