this docu update mentions that cell phones also use cdc-acm.

Signed-off-by: Oliver Neukum <oliver@neukum.name>

Now that devfs is removed, there's no longer any need to document how to
do this or that with devfs.

This patch includes some improvements by Joe Perches.

Signed-off-by: Adrian Bunk <bunk@stusta.de>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!