MAINTAINERS: add a mailing list for DAMON development

This commit adds an open mailing list for DAMON in MAINTAINERS file.

Link: https://lkml.kernel.org/r/20220503180741.137079-1-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>