Documentation/SubmittingPatches: update some dead URLs

The links to "The perfect patch" and "NO!!!! No more huge patch
bombs..." have gone stale. Update them to some working locations.

Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>