doc/admin-guide/cgroup-v2: use tables

These two places are rendered like a table in the source (rst) code,
but they are seen as plain text by formatters, and thus are joined
together into a single line, e.g.:

> “root” - a partition root “member” - a non-root member of a partition

This is definitely not what was intended.

To fix, use table formatting, like in other places.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210120001824.385168-9-kolyshkin@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/cgroup-v2.rst

@@ -2005,8 +2005,10 @@ Cpuset Interface Files
 
 	It accepts only the following input values when written to.
 
-        "root"   - a partition root
-        "member" - a non-root member of a partition
+	  ========	================================
+	  "root"	a partition root
+	  "member"	a non-root member of a partition
+	  ========	================================
 
 	When set to be a partition root, the current cgroup is the
 	root of a new partition or scheduling domain that comprises
@@ -2047,9 +2049,11 @@ Cpuset Interface Files
 	root to change.  On read, the "cpuset.sched.partition" file
 	can show the following values.
 
+	  ==============	==============================
 	  "member"		Non-root member of a partition
 	  "root"		Partition root
 	  "root invalid"	Invalid partition root
+	  ==============	==============================
 
 	It is a partition root if the first 2 partition root conditions
 	above are true and at least one CPU from "cpuset.cpus" is