Add Staryu macropad support (#2768)

* 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

* Staryu: initial port

* Add personal keymap

* Added and updated READMEs

* Fix: default keymap for staryu

* Rudimentary backlight support.

* Enabled mousekeys for default keymap

* use QMK_KEYBOARD_H and LAYOUT

* Update readme.md for NIU mini: flash using avrdude

* Fix missing linebreaks for Staryu README

* Update readme.md

keyboards/staryu/readme.md

@@ -0,0 +1,15 @@
+# Staryu
+
+![Staryu](https://i.imgur.com/obcCpZN.jpg)
+
+A 5 key macropad, designed by Kai and sold by KPRepublic.
+
+Keyboard Maintainer: QMK Community  
+Hardware Supported: Staryu (only the non-lite version has been tested)  
+Hardware Availability: [AliExpress](https://www.aliexpress.com/item/Staryu-Mini-Macro-Pad-custom-keyboard-by-tkg-kai-Mini-macro-pad-mechanical-keyboard-5-keys/32817560746.html)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make staryu:default
+
+See [build environment setup](https://docs.qmk.fm/build_environment_setup.html) then the [make instructions](https://docs.qmk.fm/make_instructions.html) for more information.