FAQ: for command centric AB dists

[plicease]

Suggested based on interaction on IRC

<hobbs> plicease: btw, what do you think of a FAQ entry something like "Q: Can I use Alien::Base
for programs too? A: Yes, most of the docs talk about libraries, but you can look at L<Alien::bison> 
for an example of how to check for a program, build it if it's not there, and ensure it's in the user's 
PATH."

This is on my todo list unless somebody wants to do it first.

[plicease]

covered by #176, any further discussion can continue there.