Prefer SessionSockdirGroup to be set to 'root'

With recent changes to the SCP interface, the xrdp process no longer
needs read access to the user sockdir when sesman is in use.

sesman/sesman.ini.in

@@ -48,8 +48,14 @@ RestrictInboundClipboard=none
 #XorgNoNewPrivileges=true
 ; Specify the group which is to have read access to the directory where
 ; local sockets for the session are created.
-; This MUST be the same as runtime_group in xrdp.ini, or xrdp will not
-; be able to connect to your sessions.
+; This should take one of the following values:-
+; 1) For normal operation with sesman, set this to 'root' for
+;    maximum security
+; 2) If you are using xrdp to connect to VNC sessions with X server
+;    sockets or chansrv sockets in the local sockets dir, set this to
+;    the runtime_group in xrdp.ini. If you do not do this, xrdp will not
+;    be able to connect to your sessions.
+SessionSockdirGroup=root
 #SessionSockdirGroup=xrdp