doc, mm: sync up oom_score_adj documentation

There are at least two notes in the oom section.  The 3% discount for root
processes is gone since d46078b2 ("mm, oom: remove 3% bonus for
CAP_SYS_ADMIN processes").

Likewise children of the selected oom victim are not sacrificed since
bbbe4802 ("mm, oom: remove 'prefer children over parent' heuristic")

Drop both of them.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: http://lkml.kernel.org/r/20200709062603.18480-1-mhocko@kernel.org


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>