/usr/src/UPGRADING procedure info

[Justin C. Sherrill]

Justin C. Sherrill wrote:

> Then, does anyone have an objection to making that the default behavior of
> the supplied cvsup file?  That would match the way I plan to document it.

Jeremy Almey pointed out to me that this would make it difficult to revert
to an older version of a file; however, it would be workable once separate
tags are available for "stable"/"development" versions, as the "stable"
code shouldn't suddenly break.