document that you probably cannot talk to ldap directly

tsa/howto/ldap.mdwn

@@ -185,6 +185,10 @@ This will list all known hosts in LDAP:
 
     ldapsearch -ZZ -vLxW -h db.torproject.org -D "uid=$USER,ou=users,dc=torproject,dc=org" -b "ou=hosts,dc=torproject,dc=org" '(objectclass=*)' | grep ^dn:
 
+Note that this will only work on the LDAP host itself or on
+whitelisted hosts which are few right now. This is mostly documented
+for TPA members.
+
 Modifying the schema
 --------------------