add API link to README
add API link to README

BrainJS/brain.js,nickpoorman/brain,ClimbsRocks/warmBrain,antares500/brain,ckknight/brain,renatoargh/brain,mcanthony/brain,polymaths/brain,saidimu/brain,dpraimeyuu/brain,andyfoster/brain,ClimbsRocks/brain,valgaze/brain,drewry/brain,kuychaco/brain,harthur-org/brain,lichterschalter/brain,adrianseeley/brain,ThiagoGarciaAlves/brain,Django0505/brain,urandu/brain,kustomzone/brain,richard512/brain,Ossehoht/brain,chrisearl/brain,daysmingming/brain,harthur-org/brain.js,datachand/brain,dexterbrylle/brain,webmechanicx/brain,theiver9827/brain,gdseller/brain,trongr/brain,mrStiven/brain,harthur/brain,martinstarman/brain,elkingtonmcb/brain,stndlkr200/brain