Documentation: cgroup v2: Trivial heading correction.

Corrected the heading to match with index.
Signed-off-by: Parav Pandit <pandit.parav@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Documentation/cgroup-v2.txt

@@ -898,7 +898,7 @@ PAGE_SIZE multiple when read back.
 	limit, anonymous meomry of the cgroup will not be swapped out.
 
 
-5-2-2. General Usage
+5-2-2. Usage Guidelines
 
 "memory.high" is the main mechanism to control memory usage.
 Over-committing on high limit (sum of high limits > available memory)