Update Documentation: Including install procedure

Morning all:

I've just published a new update to the chapter in the doc that
discusses the new Maven build system. 

http://www.keelframework.org/release/HEAD/docbook/keel-doc/html_chunk/manual/ch13.html#d0e5613

You will also find on there instructions for initially installing Keel
itself via Maven - I think you'll find this procedure far simpler than
the old method of getting a whole CVS snapshot.

So far on the "default" example project has been set up to work with
this new build technique, but I hope to have the remainder of the
projects converted today, as it's not difficult to set up.

I will publish updates to this doc frequently, and would appreciate any
feedback, especially if the instructions don't work!

Regards,

Mike

P.S. One small addition already: There's a mirror of maven-1.0.2 at
http://www.keelframework.org/maven/maven-1.0.2.zip, just for
convenience.