Slipped my radar, but here is a patch for https://fedorahosted.org/sssd/ticket/2683


diff --git a/src/man/sssd.conf.5.xml b/src/man/sssd.conf.5.xml
index 573f421..c17e8c4 100644
--- a/src/man/sssd.conf.5.xml
+++ b/src/man/sssd.conf.5.xml
@@ -509,6 +509,10 @@ subdomain_inherit = ldap_purge_cache_timeout
                         <para>
                             Default: none
                         </para>
+                        <para>
+                            Note: This option only works with the ipa provider
+                            and AD trust setup.
+                        </para>
                     </listitem>
                 </varlistentry>
             </variablelist>