Updated personal keymaps, fixed Let's Split default keymap, updated JJ40 README (#2704)
* Add M6-A keymap
* Update XD60 keymap
* Update XD60 keymap readme
* Update JJ40 and Let's Split keymaps
* Add readme for M6-A
* Fix typo, update JJ40 README
* Update jj40 readme
* Cleanup jj40 keymap
* Revert Let's Split QWERTY layer to default before #2010
* Update numpad layers
* Fix: Let's Split keymap getting stuck mods due to having keycodes assigned on the Raise layer
* Keep ASCII art consistent with keymap
d3c6da7aff