[Docs] Add dedicated page for Split Keyboard information (#5802)

[Docs] Add dedicated page for Split Keyboard information (#5802)

* [Docs] Add dedicated page for Split Keyboard information

* Apply suggestions from code review

Co-Authored-By: drashna <drashna@live.com>
* Fix Typos

Co-Authored-By: drashna <drashna@live.com>
* Fix some formatting issues

* Add Additional RGB info

* Fix Bulletted formatting

* Apply suggestions from code review

Co-Authored-By: drashna <drashna@live.com>
* Fix line wrapping

* Additional fixes and expansion

* Reword warning/note

Co-Authored-By: drashna <drashna@live.com>
* add i2c/serial coexistance info

* i2c markdown

* Change i2c wiring text

Co-Authored-By: drashna <drashna@live.com>