Mention what the ssh -M session looks like.

doc/darcs.html

@@ -219,6 +219,11 @@ Start the master connection:
 </PRE>
 <P></P>
 <P>
+This looks just like a normal ssh login, and you get a shell on the server.
+Put this connection in the background, or keep it open in a window
+somewhere.
+</P>
+<P>
 <B>NOTE: You need to have a ControlMaster connection running whenever you want to access the repo using ssh.</B>
 You may want to create a script or alias for starting the connection.
 </P>

doc/darcs.txt

@@ -165,6 +165,10 @@ Start the master connection:
 $ ssh -M gfreposerver
 ```
 
+This looks just like a normal ssh login, and you get a shell on the server.
+Put this connection in the background, or keep it open in a window
+somewhere.
+
 **NOTE: You need to have a ControlMaster connection running whenever you want to access the repo using ssh.**
 You may want to create a script or alias for starting the connection.