MAN: Document which principal does the AD provider use Administrators are often confused by the difference between what principal is used to authenticate to AD. Let's document that. Reviewed-by: Pavel Březina <pbrezina@redhat.com>

MAN: Document different defaults for AD provider Update man pages for any AD provider config options that differ from ldap/krb5 provider back-end defaults Resolves: https://fedorahosted.org/sssd/ticket/3214 Reviewed-by: Jakub Hrozek <jhrozek@redhat.com> Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>