Update docs/proposals/authentication-filter.md

Co-authored-by: Saylor Berman <s.berman@f5.com>

Author: shaun-nx

docs/proposals/authentication-filter.md

@@ -970,6 +970,7 @@ type NamespacedSecretKeyReference struct {
 
 For initial implementaion, both Basic Auth and Local JWKS should will only  have access to Secrets in the same namespace.
 
+Example: Grant BasicAuth in app-ns to read a Secret in security-ns
 Example: Grant BasicAuth in app-ns to read a Secret in security-ns
 
 ```yaml