break feature_advanced_keycodes.md up into multiple files

improve our docsify setup

fix numbering

overhaul the newbs guide

More sidebar organization

Add API documentation

update flashing.md

- minor typo on intro paragraph (the -> them)
- remove note about :check-size target (`make` task now does this automatically)
- heading level for Caterina commands section
- typo regarding Halfkay (come -> comes)

update newbs_building_firmware.md

Update the text sample for when the compile task completes.

Rework the newbs guide around the qmk cli

Add dark mode support

_summary.md: move Auto Shift page to Software Features category

clean up links to keycode references in newbs_building_firmware_configurator.md

clean up callouts in newbs_building_firmware_configurator.md

remove some unnecessary external links

Also clean up some trailing whitespace.

rework the index page

remove unused docs

more wip

wip

[Keyboard] add miller/gm-862 keyboard (#8230)

* add miller/gm-862 keyboard

* Update keyboards/miller/gm862/gm862.c

* Update keyboards/miller/gm862/gm862.h

* Update keyboards/miller/gm862/gm862.h

* Update keyboards/miller/gm862/readme.md

* Update keyboards/miller/gm862/readme.md

* Update keyboards/miller/gm862/readme.md

* Update keyboards/miller/gm862/readme.md

* Update config.h

* Update keyboards/miller/gm862/config.h

* Update keyboards/miller/gm862/readme.md

update lily58/rev1:yshrsmz (#8298)

* update lily58/rev1:yshrsmz

* use pre-shifted keycodes