Add Google-specific note about visibility checking in //experimental.

PiperOrigin-RevId: 406060379
diff --git a/site/docs/visibility.md b/site/docs/visibility.md
index 37967ea..e2daa2e 100644
--- a/site/docs/visibility.md
+++ b/site/docs/visibility.md
@@ -16,6 +16,7 @@
 If you need to disable the visibility check (for example when experimenting),
 use `--check_visibility=false`.
 
+
 For more details on package and subpackages, see
 <a href="build-ref.html">Concepts and terminology</a>.