Add Documentation target
Add appledoc note to bootstrap script
Use `command -v` to check for `appledoc` dependency

Seemingly that or `hash`/`type` are the [preferred way][pw] to check if
a program exists. Probably an unnecessary change for this little script
that will run on Macs, but ¯\_(ツ)_/¯.

[pw]: http://stackoverflow.com/a/677212
Merge pull request #4 from cdzombak/cdz/documentation

Add an appledoc build target