message: authz: fix RBAC filter config PB docs
  Fix the description of an `RBAC` Protobuf message example, so that it
  matches the changes made to the YAML code block in PR
  Risk Level: Low
  Testing: N/A
  Docs Changes: N/A
  Release Notes: N/A
diff: @@ -16,12 +16,11 @@ option go_package = "v2alpha";
  //
  // Here is an example of RBAC configuration. It has two policies:
  //
  -// * Service account "cluster.local/ns/default/sa/admin" has full access (empty permission entry
  -// means full access) to the service.
  +// * Service account "cluster.local/ns/default/sa/admin" has full access to the service, and so
  +// does "cluster.local/ns/default/sa/superuser".
  //
  -// * Any user (empty principal entry means any user) can read ("GET") the service at paths with
  -// prefix "/products" or suffix "/reviews" when request header "version" set to either "v1" or
  -// "v2".
  +// * Any user can read ("GET") the service at paths with prefix "/products", so long as the
  +// destination port is either 80 or 443.
  //
  // .. code-block:: yaml
  //
  