Update README.md

Author: Musealali

umbraco-cloud/set-up/project-settings/manage-hostnames/README.md

@@ -17,6 +17,9 @@ The hostnames contain the region on which your project is hosted. Currently, the
 * Australian East (aueast01)
 
 To access the backoffice, add `/umbraco` at the end of the Live, Development, or Staging URL.
+{% hint style="info" %}
+Limitation: A maximum of 100 hostnames can be configured for /umbraco login access.
+{% endhint %}
 
 ## Domains