Update the hacking guide, before CONFIG_PREEMPT_RT goes in and it needs
rewriting again.

Changes include modernization of quotes, removal of most references to
bottom halves (some mention required because we still use bh in places to
mean softirq).

It would be nice to have a discussion of sparse and various annotations.
Please send patches straight to akpm.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (authored)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>