added citation to readme
added citation to readme

strongh/GPy,TianpeiLuke/GPy,strongh/GPy,gusmaogabriels/GPy,mikecroucher/GPy,AlexGrig/GPy,dhhjx880713/GPy,fivejjs/GPy,mikecroucher/GPy,PredictiveScienceLab/GPy,avehtari/GPy,dhhjx880713/GPy,avehtari/GPy,ysekky/GPy,mikecroucher/GPy,avehtari/GPy,ptonner/GPy,befelix/GPy,ptonner/GPy,buntyke/GPy,AlexGrig/GPy,esiivola/GPYgradients,ptonner/GPy,dhhjx880713/GPy,SheffieldML/GPy,beckdaniel/GPy,ptonner/GPy,jameshensman/GPy,AlexGrig/GPy,maaskola/GPy,maaskola/GPy,beckdaniel/GPy,Dapid/GPy,gusmaogabriels/GPy,dhhjx880713/GPy,ysekky/GPy,mikecroucher/GPy,beckdaniel/GPy,avehtari/GPy,SheffieldML/GPy,ysekky/GPy,TianpeiLuke/GPy,maaskola/GPy,jameshensman/GPy,fivejjs/GPy,strongh/GPy,fivejjs/GPy,buntyke/GPy,jameshensman/GPy,maaskola/GPy,jameshensman/GPy,buntyke/GPy,befelix/GPy,PredictiveScienceLab/GPy,esiivola/GPYgradients,befelix/GPy,Dapid/GPy,ysekky/GPy,TianpeiLuke/GPy,befelix/GPy,AlexGrig/GPy,beckdaniel/GPy,PredictiveScienceLab/GPy,esiivola/GPYgradients,Dapid/GPy,SheffieldML/GPy,esiivola/GPYgradients,buntyke/GPy,gusmaogabriels/GPy,Dapid/GPy,PredictiveScienceLab/GPy,SheffieldML/GPy