fix links in readme
fix links in readme

the ! is for adding images, but these are just links

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