applied Gottox' comment fix (thanks)

dwm.c

@@ -15,7 +15,7 @@
  *
  * Each child of the root window is called a client, except windows which have
  * set the override_redirect flag.  Clients are organized in a global
- * doubly-linked client list, the focus history is remembered through a global
+ * linked client list, the focus history is remembered through a global
  * stack list. Each client contains a bit array to indicate the tags of a
  * client.
  *