[Keymap] Add Endemoniada keymaps (#6875)

[Keymap] Add Endemoniada keymaps (#6875)

* Add dz60 keymap

* Add my TADA68 layout

* Fix descriptions and formatting

* Formatting fixes

* Add readme file

* Formatting

* move caps lock to correct key, add F-keys to both layers

* Add readme for dz60

* First draft of custom Let's Split layout

* Some more keys

* Finalized keymap

* Added a bunch of custom shortcuts to make layout easier to read

* Add PERMISSIVE_HOLD option to modtap behavior

* Add lock and sleep shortcuts, formatting

* Minor fixes and adjustments

* Add PERMISSIVE_HOLD option, add sleep/lock shortcuts, minor fixes

* Add sleep/lock shortcuts, minor fixes

* fixups

* Major simplification of lets_split layout into more standard raise/lower/special layers

* Remove layer songs, add to readme

* Formatting

* Switch a few keys around for reachability

* Add windows/mac specific layers

* simplify layers

* Update README

* Fix legends

* Invert numpad and put Del in upper right corner

* Disable arrow keys on Raise, add build instructions

* Move dz60 keymap to its own branch

* Remove redundant configuration

* Change volume and sleep keycodes to standard

* Removing empty rules.mk

* Changing layer defines to enum

* Adding comment to explain reason for swapping KC_TRNS and KC_NO fillers