* etc/NEWS: Improve XDG_RUNTIME_DIR doc.

etc/NEWS

@@ -222,7 +222,7 @@ The command-line argument '--socket-name' overrides it.
 +++
 *** Emacs and emacsclient now default to "$XDG_RUNTIME_DIR/emacs"
 as the directory for client/server sockets, if Emacs is running
-under an X Window System desktop that sets the 'XDG_RUNTIME_DIR'
+on a platform or environment that sets the 'XDG_RUNTIME_DIR'
 environment variable to indicate where session sockets should go.
 To get the old, less-secure behavior, you can set the
 'EMACS_SOCKET_NAME' environment variable to an appropriate value.