docs: clarify member-only profile instructions (#41868)

Co-authored-by: Felix Guntrip <guntrip@github.com>

Author: mbainter

content/organizations/collaborating-with-groups-in-organizations/customizing-your-organizations-profile.md

@@ -56,6 +56,8 @@ The content of public `README.md` will appear on your organization's public prof
 
 ## Adding a member-only organization profile README
 
+>[!NOTE] Member-only organization profile READMEs will only load from a `.github-private` repository with its visibility set to private. Repositories in enterprises set to internal visibility will not work.
+
 The content of a member-only `README.md` will be displayed in the member view of your organization's profile.
 
 1. If your organization does not already have a `.github-private` repository, create a private repository called `.github-private`.