SFOS: Add notice to documentation, that Active Directory Group Nesting is unsupported

Please add to the documentation (all SFOS Versions) that nested / staggered Active Directory Groups (Group in a Group) are unsupported. This is currently unmentioned.

Here:

https://docs.sophos.com/nsg/sophos-firewall/19.0/Help/en-us/webhelp/onlinehelp/AdministratorHelp/Authentication/HowToArticles/AuthenticationActiveDirectoryGroupBehavior/index.html

Answer by Sophos' Lucar Toni here:

 RE: AD Authentication, Nested / Staggered Groups not working