Update channel definitions
Update channel definitions

Added stable channel definitions for consistency with other pages.
ksmaheshkumar/docs-2,iankronquist/docs,bq-xiao/docs,hkjn/docs-1,joshix/docs,skynet/docs,coreos/docs,michelleN/docs,marineam/coreos-docs,robszumski/docs,mischief/coreos-docs,jonboulle/docs,mjg59/docs,ionave/docs,atxwebs/docs,endocode/coreos-docs,wli6/docs,jdloft/docs