Add recipe for pinky-mode, a minor mode to reduce strain on pinkies

Hello! This request is to add a recipe for pinky-mode, a minor mode which is intended to reduce strain on pinkies by altering key bindings. While pinky-mode is active, letter keys invoke common navigation commands instead of inserting text. For example, you can go to the next line (`next-line`) by pressing `n` instead of `C-n`. Pressing `i` exits pinky-mode.

pinky-mode is maintained at https://github.com/jayconrod/pinky-mode

I'm the creator of this package. I've verified this builds with `make recipes/pinky-mode` and installs with `M-x package-install-file`.

This is my first contribution to Melpa, so please let me know if I should fix anything.

Thanks!