- explictly say not to edit infrastructure for vendor ids (not just the
ids).
- say to enclose vendor ids and their infrastucture in ``#if 0'', and
partly explain why.
- don't set a bad example by mangling the Berkeley id infrastructure from
``static char sccsid[] ...'' to ``__RCSID(...)''.
- show a blank line between the vendor id cruft and the FreeeBSD if cruft
in the example.
- relaxed the rule about adding "From: " to say that "From: " is actually
useful if the file has been renamed.
- minor English improvements.
Discussed with: obrien
d705353edb