doc: update API info in README.md
doc: update API info in README.md

giantswarm/fleet,bviswana101/fleet,ecnahc515/fleet,mwitkow-io/fleet,jonboulle/fleet,dalbani/fleet,ecnahc515/fleet,esatterwhite/fleet,improbable-io/fleet,bcwaldon/fleet,mischief/fleet,dalbani/fleet,bcwaldon/fleet,wuqixuan/fleet,giantswarm/fleet,paveltiunov/fleet,mwitkow-io/fleet,thepwagner/fleet,mookjp/fleet,dalbani/fleet,mwhooker/fleet,thepwagner/fleet,hhoover/fleet,flandr/fleet,hhoover/fleet,giantswarm/fleet,bviswana101/fleet,esatterwhite/fleet,mwitkow/fleet,wuqixuan/fleet,jonboulle/fleet,improbable-io/fleet,coreos/fleet,mookjp/fleet,webwlsong/fleet,mwhooker/fleet,octoblu/fleet,dongsupark/fleet,bcwaldon/fleet,endocode/fleet,mischief/fleet,paveltiunov/fleet,WPMedia/fleet,octoblu/fleet,flandr/fleet,webwlsong/fleet,endocode/fleet,jonboulle/fleet,improbable-io/fleet,dongsupark/fleet,mwitkow/fleet,coreos/fleet,ecnahc515/fleet,endocode/fleet,dongsupark/fleet,WPMedia/fleet,coreos/fleet