Add vim arrow keymap for hhkb

[Gyong1211]

Hello Hasu,

I make vim arrow keymap (Control + H, J, K, L to left, down, up, right arrows)

It was tested on my hhkb and there was no problem.

Thank you.

[tmk]

Great. Wikified in 'Keymap examples' page. Thank you.
https://github.com/tmk/tmk_keyboard/wiki/Keymap-examples

This won't be merged see this post about my thought on user's keymaps file and ideas.
#265 (comment)

[Gyong1211]

Thank you. I close this issue