Merge pull request #12 from jminor/fix_dupe

Touchpad was listed twice in DeviceButton docs.

api/lovr/headset/DeviceButton.lua

@@ -25,10 +25,6 @@ return {
       name = 'menu',
       description = 'The menu button.'
     },
-    {
-      name = 'touchpad',
-      description = 'The button on the touchpad.'
-    },
     {
       name = 'a',
       description = 'The A button.'