Added cookie endpoints to readme.
Added cookie endpoints to readme.

shaunstanislaus/httpbin,Stackato-Apps/httpbin,paranoiasystem/httpbin,bradparks/httpbin__http_echo_service_for_testing_http_requests,hnq90/httpbin,pskrz/httpbin,postmanlabs/httpbin,gvangool/httpbin,sigmavirus24/httpbin,yemingm/httpbin,shaunstanislaus/httpbin,Runscope/httpbin,paranoiasystem/httpbin,ashcoding/httpbin,kennethreitz/httpbin,cityindex-attic/python-development-flow,vscarpenter/httpbin,Jaccorot/httpbin,vscarpenter/httpbin,pestanko/httpbin,scottydelta/httpbin,logonmy/httpbin,mojaray2k/httpbin,logonmy/httpbin,Lukasa/httpbin,gvangool/httpbin,tatsuhiro-t/httpbin,mansilladev/httpbin,postmanlabs/httpbin,pskrz/httpbin,phouse512/httpbin,SunGuo/httpbin,hnq90/httpbin,habibmasuro/httpbin,admin-zhx/httpbin,OndrejPontes/httpbin,ewdurbin/httpbin,yemingm/httpbin,OndrejPontes/httpbin,cityindex-attic/python-development-flow,nkhuyu/httpbin,mozillazg/bustard-httpbin,habibmasuro/httpbin,scottydelta/httpbin,Lukasa/httpbin,lioonline/httpbin,fangdingjun/httpbin,krissman/httpbin,SunGuo/httpbin,fangdingjun/httpbin,bradparks/httpbin__http_echo_service_for_testing_http_requests,sigmavirus24/httpbin,cityindex-attic/python-development-flow,luosam1123/httpbin,marinehero/httpbin,krissman/httpbin,Runscope/httpbin,luhkevin/httpbin,luosam1123/httpbin,nkhuyu/httpbin,Stackato-Apps/httpbin,mansilladev/httpbin,marinehero/httpbin,pestanko/httpbin,Jaccorot/httpbin,luhkevin/httpbin,kennethreitz/httpbin,ewdurbin/httpbin,mozillazg/bustard-httpbin,phouse512/httpbin,yangruiyou85/httpbin,mojaray2k/httpbin,yangruiyou85/httpbin,ashcoding/httpbin,admin-zhx/httpbin,lioonline/httpbin