[doc] add a note to visibility specification to avoid confusion
PiperOrigin-RevId: 401316402
diff --git a/site/docs/visibility.md b/site/docs/visibility.md
index 1762ead..6bae708 100644
--- a/site/docs/visibility.md
+++ b/site/docs/visibility.md
@@ -57,6 +57,8 @@
As a special case, `package_group` targets themselves do not have a `visibility`
attribute; they are always publicly visible.
+Visibility cannot be set to specific non-package_group targets. That triggers a "Label does not refer to a package group" or "cycle in dependency graph" error.
+
## Visibility of a rule target
If a rule target does not set the `visibility` attribute, its visibility is
