Improved README of yuuki and added RGB commands (#1983)

Improved README of yuuki and added RGB commands (#1983)

* Add yuuki keymap

Documentation is still a TODO and the keymap may not be final

* GRV on colon

* add KC_GRV to FN ESC

* more RGB modes

* Update README.md

Add image of layout and fix typo

* switch from jpg to png

For some reason the JPG had red outlines around the keys.

* remove whitespace

* add instruction to reset keyboard before flashing

* gh60 stytle layout

* moved the GH60 style layout to new folder

* add HOME and END

* Add heading

* moved ayanami to other branch