* m75s.h: correct matrix position identifier
`K5C` is actually on row 4, so it should be `K4C`.
* m75s.h: add matrix diagram
* add QMK Configurator data
* polish whitespace
- convert tabs to spaces
- update indent to four spaces
- remove trailing whitespace
* update readme
Didn't seem to be fully updated after being copied from the M65S codebase.
* add LAYOUT_ansi with keymap
ANSI layout with 2u Backspace.
* add LAYOUT_iso with keymap
ISO layout with 2u Backspace.
* add LAYOUT_ansi_tsangan with keymap
ANSI layout with 2u Backspace and 7u Spacebar.
* add LAYOUT_iso_tsangan with keymap
ISO layout with 2u Backspace and 7u Spacebar.
* add LAYOUT_ansi_split_bs with keymap
ANSI layout with Split Backspace.
* add LAYOUT_iso_split_bs with keymap
ISO layout with Split Backspace.
* add LAYOUT_ansi_tsangan_split_bs with keymap
ANSI layout with Split Backspace and 7u Spacebar.
* add LAYOUT_iso_tsangan_split_bs with keymap
ISO layout with Split Backspace and 7u Spacebar.
