Our current tag for this concept is cgroups.
However, according to the official kernel documentation:
“cgroup” stands for “control group” and is never capitalized. The singular form is used to designate the whole feature and also as a qualifier as in “cgroup controllers”. When explicitly referring to multiple individual control groups, the plural form “cgroups” is used.
I know you can't legislate language usage, but it would be good to have our tag usage correspond to the official documentation (in my opinion).