RFC: 5.3 Migration Guide

Howdy--

I've volunteered to rework the 5.X Early Adopters Guide into a Migration
Guide.  The focus of this document is less about discouraging unwary
users and more about what kinds of changes users might encounter when
they move from 4.X to 5.X.

I'd like to solicit a pre-commit review on the document at:

http://people.freebsd.org/~bmah/pub/article.html

A PDF rendering, as well as SGML source, also live in the same
directory.

The area I'm the most shaky on is the source upgrade procedure, which is
basically an annotated version of the procedure in src/UPDATING.  I
haven't done this procedure in a *long* time, and I'm kind of short on
scratch systems (=> none) at the moment for testing the procedure.  In
retrospect, I didn't actually plan on including this section, and I
might have been less eager to take on this task if I'd know it was
coming.  :-)

trhodes and scottl provided some helpful feedback on an earlier draft of
this document.

Thanks for any comments...

Bruce.

PS.  This document will basically replace the EAG for 5.3.  On HEAD, we
should probably disable or kill the EAG.  It's served its purpose (I
think) and when it comes back in time for 6.0, it probably won't bear
much resemblance to its current incarnation.