cgroup_misc: add kernel-doc comments for enum misc_res_type
Fully document enum misc_res_type with kernel-doc comments to prevent
kernel-doc warnings:
misc_cgroup.h:12: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Types of misc cgroup entries supported by the host.
misc_cgroup.h:12: warning: missing initial short description on line:
* Types of misc cgroup entries supported by the host.