[PATCH] docs: fix misinformation about overcommit_memory

Someone complained about the docs for vm_overcommit_memory being wrong.
This patch copies the text from the vm documentation into procfs.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>