zsmalloc: document new fullness grouping

zsmalloc: document new fullness grouping

Patch series "zsmalloc: minor documentation updates".

Two minor patches that bring zsmalloc documentation up to date.

This patch (of 2):

Update documentation and reflect new zspages fullness grouping (we don't
use almost_empty and almost_full anymore).

Link: https://lkml.kernel.org/r/20230325024631.2817153-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20230325024631.2817153-2-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Fixes: 67e157eb3639 ("zsmalloc: show per fullness group class stats")
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>