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

keyboards/rama/m6_a/keymaps/krusli/README.md

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+# krusli's RAMA M6-A Layout
+
+Personal keymap for the RAMA M6-A.
+
+Keymap was from my own port for the M6-A before official support was added, thus the backlighting code is not ported yet from the official default keymap.
+
+Top-right button acts as a "toggle between layers" button. Layer 0 -> Layer 1 -> Layer 2 -> Layer 0 -> ...
+
+- Layer 0: Git and Discord shortcuts
+- Layer 1: Media playback and volume controls
+- Layer 2: Osu! gamepad layer
+
+## Helpful alternative keymaps (WIP)
+### Arrow cluster
+Use [karabiner-elements](https://github.com/tekezo/Karabiner-Elements) on macOS so that the state of the modifiers (shift, caps lock) are synchronised between keyboards (for shift + arrow key text selection, for example). It's also a handy tool for customising keyboard behaviour on a Mac.
+
+On Windows/Linux modifier state should be shared between all keyboards by default.
+
+Installation: install [homebrew](https://brew.sh) and run `brew install Caskroom/cask/karabiner-elements`.
+
+```C
+KEYMAP(
+  KC_ESC,   KC_UP,   TO(_LAYER0),
+  KC_LEFT,  KC_DOWN, KC_RIGHT
+)
+```

keyboards/rama/m6_a/keymaps/krusli/keymap.c

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+#include "../../m6_a.h"
+#include "action_layer.h"
+#include "eeconfig.h"
+
+extern keymap_config_t keymap_config;
+
+// Each layer gets a name for readability, which is then used in the keymap matrix below.
+// The underscores don't mean anything - you can have a layer called STUFF or any other name.
+// Layer names don't all need to be of the same length, obviously, and you can also skip them
+// entirely and just use numbers.
+
+enum layers {
+  _LAYER0,
+  _LAYER1,
+  _LAYER2
+};
+
+enum custom_keycodes {
+  GIT_ADD = SAFE_RANGE,
+  GIT_COMMIT,
+  GIT_PUSH,
+  MUTE,
+  DEAFEN
+};
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+	if (record->event.pressed) {
+		switch(keycode) {
+			case GIT_ADD:
+				SEND_STRING("git add ."SS_TAP(X_ENTER));
+        break;
+      case GIT_COMMIT:
+        SEND_STRING("git commit -m "SS_DOWN(X_LSHIFT)SS_TAP(X_QUOTE)SS_UP(X_LSHIFT));
+        break;
+      case GIT_PUSH:
+        SEND_STRING("git push"SS_TAP(X_ENTER));
+        break;
+      case MUTE:
+        SEND_STRING(SS_LGUI(SS_LSFT("M")));
+        break;
+      case DEAFEN:
+        SEND_STRING(SS_LGUI(SS_LSFT("D")));
+        break;
+      return false;
+		}
+	}
+	return true;
+};
+
+#define _______ KC_TRNS
+#define XXXXXXX KC_NO
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+  [_LAYER0] = KEYMAP(
+    MUTE,    DEAFEN,     TO(_LAYER1),
+    GIT_ADD, GIT_COMMIT, GIT_PUSH
+  ),
+  [_LAYER1] = KEYMAP(
+    KC_VOLD, KC_VOLU, TO(_LAYER2),
+    KC_MRWD, KC_MPLY, KC_MNXT
+  ),
+  [_LAYER2] = KEYMAP(
+    KC_ESC,  KC_UP,   TO(_LAYER0),
+    KC_Z,    KC_X,    KC_SPACE
+  )
+};
+
+void matrix_init_user(void) {
+  #ifdef BACKLIGHT_ENABLE
+    backlight_level(0);
+  #endif
+}