docs/43941: document the Rationale for Upgrade Sequence (e.g. why the "historical" build sequence is deprecated)

[keramida at FreeBSD.org]

Synopsis: document the Rationale for Upgrade Sequence (e.g. why the "historical" build sequence is deprecated)

Responsible-Changed-From-To: freebsd-doc->keramida
Responsible-Changed-By: keramida
Responsible-Changed-When: Wed Jan 16 07:08:50 UTC 2008
Responsible-Changed-Why: 
Grab PR; I'll try to integrate the text of Tim to the Handbook

http://www.freebsd.org/cgi/query-pr.cgi?pr=43941