kbuild: patch to Documentation/kbuild/modules.txt

First off, thanks for the kbuild docs, they are very useful!  Second,
I've attached a patch to modules.txt (from 2.6.14.2) with a "compile"
fix to a Makefile example, and some trivial spelling/grammar nits.
Please let me know if you want the patch in some other format (eg not
MIME), or if I should go bother someone else about it.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>