[Toaster] Changes to the Toaster manual

[Barros Pena, Belen]

I have gone through the list of changes we put together for the Toaster
manual, and most of them are already there. There is only one thing
pending: changing Chapter 3, the one about setting up and using Toaster.

The team has put together some new content for that section as a starting
point. It's here

http://piratepad.nl/YzSI38RuYd

Note that it includes also some changes for section 2.1 (at the very top).

There are 2 gaps in this new content:

1. How to change the default location of the layers checkout directory
2. How to change the default location of the build directory

Brian: do you think you could add the above missing information to the
pad, so that Scott can make the changes to the manual (if he has time)?

Thanks!

Belén