* feat(nibble): add underglow support for nice_nano builds

* feat(nibble): add encoder to top, left most column to match standard assembly documentation

* refactor(nibble): add layer labels

* feat(nibble): add support for optional display ; off by default

* feat(nibble): add README

* fix(nibble): adjust oled rotation for easier reading

* fix(nibble): add additional note about enabling oled

* refactor(nibble): convert keymap to use tabs instead of spaces

* refactor(nibble): enable oled in dts/overlay by default

* refactor(nibble): cleanup alignment and formatting in nibble keymap

* refactor(nibble): re-align top most row of keymap to be sensible

* refactor(nibble): cleanup kscan map alignment

* refactor(nibble): indent first row of map/transform to properly align with physical columns

* fix(nibble): remove dangling code block from readme

Co-authored-by: KemoNine <mcrosson@kemonine.info>

The NIBBLE transformation was missing RC(0,0), which was causing some strange behavior in the kscan driver.

Aligns *.h and *.c to underscore naming convention.

These were kept (with warnings) for backwards compatibility with external boards/shields:
- kscan-mock.h
- matrix-transform.h
They should be removed in the future.

PR: #523

+ Added required files for nullbits NIBBLE