Update public-access.md

Author: jesp209i

umbraco-cloud/set-up/project-settings/public-access.md

@@ -36,3 +36,9 @@ By default, **Basic Authentication** is enabled on trial projects.
 ![Allow IPs for your Umbraco Cloud Project](../images/allow_ip.png)
 
 Once **Basic Authentication** has been enabled, users not on the project or with IPs not added to the allowlist will be prompted to log in.
+
+### CMS Basic Authentication
+
+The Umbraco Cloud Public Access feature is built on top of the Basic Authentication implementation in CMS core. This means the appsettings related to Basic Authentication are controlled by Umbraco Cloud, but your Cloud Environment has access to them. With that you can setup a httpclient that can do a loop back request without being blocked, by adding the Shared Secret Header if needed.
+
+[CMS Basic Authentication Settings](https://docs.umbraco.com/umbraco-cms/reference/configuration/basicauthsettings)