README.md: Drop the note about OS compatibility

Since we switched to using a separate node for the absolute mouse, it works with
all three major operating systems. For that reason, the note about OS
compatibility is incorrect, and with this patch, we drop it.

Reported by @noseglasses, thanks!

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

README.md

@@ -100,9 +100,6 @@ to the middle of it.
 
 To stop warping, use any other mouse key, or hit the "warp end" key.
 
-This features works out of the box on Windows and OSX. On Linux, a patch exists,
-but has not been finalised and merged yet.
-
 The warping keys are the following:
 
 * `Key_mouseWarpNW`, `Key_mouseWarpNE`, `Key_mouseWarpSW`, `Key_mouseWarpSE`: