Documentation: cgroup-v2: Sync manual toctree

Manually-arranged toctree comment in cgroup v2 documentation is a rather
out-of-sync with actual contents: a few sections are missing and/or
named differently.

Sync the toctree.

Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Documentation/admin-guide/cgroup-v2.rst

@@ -15,6 +15,9 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
 
 .. CONTENTS
 
+   [Whenever any new section is added to this document, please also add
+    an entry here.]
+
    1. Introduction
      1-1. Terminology
      1-2. What is cgroup?
@@ -25,9 +28,10 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
        2-2-2. Threads
      2-3. [Un]populated Notification
      2-4. Controlling Controllers
-       2-4-1. Enabling and Disabling
-       2-4-2. Top-down Constraint
-       2-4-3. No Internal Process Constraint
+       2-4-1. Availability
+       2-4-2. Enabling and Disabling
+       2-4-3. Top-down Constraint
+       2-4-4. No Internal Process Constraint
      2-5. Delegation
        2-5-1. Model of Delegation
        2-5-2. Delegation Containment
@@ -61,14 +65,15 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
        5-4-1. PID Interface Files
      5-5. Cpuset
        5.5-1. Cpuset Interface Files
-     5-6. Device
+     5-6. Device controller
      5-7. RDMA
        5-7-1. RDMA Interface Files
      5-8. DMEM
+       5-8-1. DMEM Interface Files
      5-9. HugeTLB
        5.9-1. HugeTLB Interface Files
      5-10. Misc
-       5.10-1 Miscellaneous cgroup Interface Files
+       5.10-1 Misc Interface Files
        5.10-2 Migration and Ownership
      5-11. Others
        5-11-1. perf_event