Add layout for each keyboard in help

[yskoht]

Before

usage: keymapviz [-h] [-c CONFIG] [-k keyboards] [-o OUTPUT] [-r]
                 [-t {ascii,json,fancy}] [-v]
                 keymap_c

keymap.c visualizer

positional arguments:
  keymap_c              keymap.c file name

optional arguments:
  -h, --help            show this help message and exit
  -c CONFIG, --config CONFIG
                        configuration file
  -k keyboards, --keyboard keyboards
                        keyboard of keymap.c
  -o OUTPUT, --output OUTPUT
                        output file name("{}" is replaced index)
  -r, --replace         replace comment block including "[keymapviz]" with ascii art. (make *.bac)
  -t {ascii,json,fancy}, --type {ascii,json,fancy}
                        type of output(default:ascii)
  -v, --version         show program's version number and exit

Following keyboards are supported.
 * crkbd
 * dactyl_manuform5x6
 * ergo42
 * ergodash
 * ergodone
 * ergodox
 * ergodox_ez
 * fortitude60
 * helix
 * kaishi65
 * kinesis
 * kyria
 * lets_split
 * lily58
 * mint60
 * moonlander
 * sofle
 * sweet16

After

usage: keymapviz [-h] [-c CONFIG] [-k keyboards] [-l layout] [-o OUTPUT] [-r]
                 [-t {ascii,json,fancy}] [-v]
                 keymap_c

keymap.c visualizer

positional arguments:
  keymap_c              keymap.c file name

optional arguments:
  -h, --help            show this help message and exit
  -c CONFIG, --config CONFIG
                        configuration file
  -k keyboards, --keyboard keyboards
                        keyboard of keymap.c
  -l layout, --layout layout
                        keyboard layout
  -o OUTPUT, --output OUTPUT
                        output file name("{}" is replaced index)
  -r, --replace         replace comment block including "[keymapviz]" with ascii art. (make *.bac)
  -t {ascii,json,fancy}, --type {ascii,json,fancy}
                        type of output(default:ascii)
  -v, --version         show program's version number and exit

Following keyboards (and layouts) are supported.
 * crkbd                (default)
 * dactyl_manuform5x6   (default)
 * ergo42               (default)
 * ergodash             (default, 2u_inner)
 * ergodone             (default)
 * ergodox              (default)
 * ergodox_ez           (default)
 * fortitude60          (default)
 * helix                (default)
 * kaishi65             (default)
 * kinesis              (default)
 * kyria                (default)
 * lets_split           (default)
 * lily58               (default)
 * mint60               (default)
 * moonlander           (default)
 * sofle                (default)
 * sweet16              (default)