Remove note about ipv4 variable support.
Remove note about ipv4 variable support.

marineam/coreos-docs,joshix/docs,mjg59/docs,iankronquist/docs,endocode/coreos-docs,hkjn/docs-1,jdloft/docs,bq-xiao/docs,ksmaheshkumar/docs-2,ionave/docs,michelleN/docs,jonboulle/docs,atxwebs/docs,coreos/docs,robszumski/docs,skynet/docs,wli6/docs,mischief/coreos-docs