Added usage to todo()

.zshrc

@@ -157,6 +157,10 @@
    }
 
    # an improved way to manage the todo list
+   # Usage:
+   #  todo                       -- edit ~/todo
+   #  todo [git command string]  -- manage todo for easy syncing, assuming ~/todo is
+   #                                a symlink that points to a file in a git repo
    todo() {
       ( # subshell to protect against directory changes
       if [ -z "$@" ];then