Re-add LED support

This reverts commit 5b069a0104.

docs/debugging.md

@@ -1,6 +1,6 @@
 # Debugging
 Debug will output most of the useful state to the console. This can be enable in your firmware
-by setting this in your keymap. NOTE that it will be MUCH slower, so only enable this when you
+by setting this in your keymap. NOTE that it will be slower, so only enable this when you
 need debugging.
 ```python
 DEBUG_ENABLE = True