Merge pull request opencontainers#800 from wking/remove-redundant-cgroup-must

config-linux: Remove redundant MUST for minimum cgroup controllers

Author: Mrunal Patel

config-linux.md

@@ -186,8 +186,7 @@ You can configure a container's cgroups via the `resources` field of the Linux c
 Do not specify `resources` unless limits have to be updated.
 For example, to run a new process in an existing container without updating limits, `resources` need not be specified.
 
-A runtime MUST at least use the minimum set of cgroup controllers required to fulfill the `resources` settings.
-However, a runtime MAY attach the container process to additional cgroup controllers supported by the system.
+Runtimes MAY attach the container process to additional cgroup controllers beyond those necessary to fulfill the `resources` settings.
 
 ###### Example