* add via support for boardsource/5x12
* make product id for 5x12 unique (there is already an 0x0512) by setting it to 0x5012
* un-swap the readme's for 3x4 and 5x12
* Update keyboards/boardsource/5x12/config.h
update vendor id
* Update keyboards/boardsource/5x12/keymaps/via/keymap.c
use correct number of layers for VIA
* update product id to use same pattern as others
* Update keyboards/boardsource/5x12/keymaps/via/readme.md
* Update keyboards/boardsource/5x12/keymaps/via/readme.md
