[PATCH] Add text for dealing with "dot releases" to README

The emergence of so-called "dot releases" that are non-incremental patches
against a base kernel requires different handling of patches (revert
previous patches before applying the newest one).  This patch adds a
paragrach to $TOPDIR/README explaining how to do deal with dot release
patches.

Signed-off-by: Kurt Wall <kwall@kurtwerks.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>