[PATCH] CodingStyle: add typedefs chapter

Add a chapter on typedefs, copied from an email from Linus to lkml on Feb.
3, 2006.  (Subject: Re: [RFC][PATCH 1/5] Virtualization/containers:
startup)

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>