[Bf-docboard] Keymap export update

[Jeffrey]

Hi doccers. I uploaded a patch to clarify the functionality of the
keymap export function in the user prefs input tab. This is my first
docs patch and docboard post. I tried to adhere to the best practices
laid out in the contribution portion of the manual, but feel free to
guide me if I need it.

Building the docs is much easier than when I first attempted years ago,
so I may be contributing much more now.

https://developer.blender.org/D1826

-- 
Jeffrey "Italic_" Hoover