[PATCH] kprobes: Update Documentation/kprobes.txt

Update Documentation/kprobes.txt to reflect Kprobes enhancements and other
recent developments.

Acked-by: Ananth Mavinakayanahalli <mananth@in.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>