Moving more extensive explanations to the end of the comment.

Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: NAristeu Rozanski <arozansk@redhat.com>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NTejun Heo <tj@kernel.org>