emacsclient: Mention GUI

pages/common/emacsclient.md

@@ -2,6 +2,10 @@
 
 > Open files in an existing emacs server.
 
+- Open files in an existing Emacs server (using GUI if available):
+
+`emacsclient {{filename}}`
+
 - Open file in console mode (without X window):
 
 `emacsclient -nw {{filename}}`