docs: zswap: fix shell command format

Format the shell commands as code block to keep the documentation in the
same style

Signed-off-by: Weiji Wang <nebclllo0444@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240319114253.2647-1-nebclllo0444@gmail.com
diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
index b4213296..1363267 100644
--- a/Documentation/admin-guide/mm/zswap.rst
+++ b/Documentation/admin-guide/mm/zswap.rst
@@ -155,7 +155,7 @@
 
 Some users cannot tolerate the swapping that comes with zswap store failures
 and zswap writebacks. Swapping can be disabled entirely (without disabling
-zswap itself) on a cgroup-basis as follows:
+zswap itself) on a cgroup-basis as follows::
 
 	echo 0 > /sys/fs/cgroup/<cgroup-name>/memory.zswap.writeback
 
@@ -166,7 +166,7 @@
 When there is a sizable amount of cold memory residing in the zswap pool, it
 can be advantageous to proactively write these cold pages to swap and reclaim
 the memory for other use cases. By default, the zswap shrinker is disabled.
-User can enable it as follows:
+User can enable it as follows::
 
   echo Y > /sys/module/zswap/parameters/shrinker_enabled