diff --git a/readme.md b/readme.md
index 83c465d5..e0ece8e7 100644
--- a/readme.md
+++ b/readme.md
@@ -718,6 +718,7 @@ What are the requirements?
 5. The container should not mount directories from the host into the container: only docker volumes should be used.
 6. The container must be usable by more than 90% of the users (e.g. not too high system requirements and such)
 7. No additional setup should be needed after adding the container - it should work completely out of the box.
+8. If the container requires being exposed, only subfolders are supported. So the container should not require its own (sub-)domain and must be able to run in a subfolder.
 
 ### How to trust user-defined Certification Authorities (CA)?
 For some applications it might be necessary to establish a secure connection to another host/server which is using a certificate issued by a Certification Authority that is not trusted out of the box. An example could be configuring LDAPS against a domain controller (Active Directory or Samba-based) of an organization.