Add rough draft guide on audio editing production

I *really* want to automate a lot of this stuff, but before I get around to solving the [general problem](https://xkcd.com/974/), I wanted to get some rough thoughts down around audio production.
Yes, it’s super frustating, but I think I know what your problem was – I too hit it.

I’m guessing that you attempted to import the *mov* files and not *mp3* files. It seems like GarageBand [freaks out and overwrites tracks when importing mov files][g1], but does [the right thing when importing mp3 (i.e., audio) files][g2].

[g1]: https://cloud.githubusercontent.com/assets/14554/4112769/9c462fc0-3238-11e4-9aea-3c682b491e25.gif
[g2]: https://cloud.githubusercontent.com/assets/14554/4112770/a33de1ce-3238-11e4-9da6-1665bb962297.gif