[PATCH] clarify help text for INIT_ENV_ARG_LIMIT

Try to make the INIT_ENV_ARG_LIMIT help text more readable and
understandable.

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