Add docs on build support setup
Add docs on build support setup

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