docs: comment out a few not-supported pcp-collectl subsystems
docs: comment out a few not-supported pcp-collectl subsystems

Pointed out by Ilan Green from Red Hat when trying to use it.

wuliming/pcp,adfernandes/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,adfernandes/pcp,wuliming/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp