Idea: Add section to manual explaining bash and environment variables

[swedebugia]

Hi

During my time in guix-land I have learned a lot about bash and 
environment variables affecting a lot of programs.

The manual is very sparse about the importance of these variables and 
does not help the users of guix on foreign distributions understand how 
they work.

http://unix.stackexchange.com/questions/88106/ddg#88108

I could write a patch for the manual if others think this is a good idea.

--
Cheers
Swedebugia