Docs/admin-guide/mm/zswap: remove zsmalloc's lack of writeback warning

Writeback has been implemented for zsmalloc, so this warning no longer
holds.

Link: https://lkml.kernel.org/r/20230106220016.172303-1-nphamcs@gmail.com
Fixes: 9997bc01 ("zsmalloc: implement writeback mechanism for zsmalloc")
Suggested-by: NThomas Weißschuh <linux@weissschuh.net>
Signed-off-by: NNhat Pham <nphamcs@gmail.com>
Reviewed-by: NSergey Senozhatsky <senozhatsky@chromium.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

Documentation/admin-guide/mm/zswap.rst

@@ -70,9 +70,7 @@ e.g. ``zswap.zpool=zbud``. It can also be changed at runtime using the sysfs
 The zbud type zpool allocates exactly 1 page to store 2 compressed pages, which
 means the compression ratio will always be 2:1 or worse (because of half-full
 zbud pages).  The zsmalloc type zpool has a more complex compressed page
-storage method, and it can achieve greater storage densities.  However,
-zsmalloc does not implement compressed page eviction, so once zswap fills it
-cannot evict the oldest page, it can only reject new pages.
+storage method, and it can achieve greater storage densities.
 
 When a swap page is passed from frontswap to zswap, zswap maintains a mapping
 of the swap entry, a combination of the swap type and swap offset, to the zpool