Document lack of support for AD domain trusts in LDAP docs

Overview

Microsoft Active Directory allows the configuration of "domain trusts" trusts allow one domain to access users on another domain (depending on the trust type). GitLab uses Net::LDAP, it's not clear if we support (or can support) an AD domain trust configuration.

Users report this doesn't work correctly. See https://forum.gitlab.com/t/using-users-from-a-domain-trust/2284, https://gitlab.zendesk.com/agent/tickets/50155

We should document that this is not supported or see if it can be supported

Documentation

• https://technet.microsoft.com/en-us/library/cc961481.aspx

• https://technet.microsoft.com/en-us/library/cc783351(v=ws.10).aspx

• https://en.wikipedia.org/wiki/Active_Directory#Trusting

• http://stackoverflow.com/questions/5051381

• http://stackoverflow.com/questions/3161566

@dblessing @stanhu