update README to show how to install CocoaPods
update README to show how to install CocoaPods

ChenYilong/ChatKit-OC,luonaerduo9/ChatKit-OC,Maru-zhang/ChatKit-OC,Maru-zhang/ChatKit-OC,Maru-zhang/ChatKit-OC,leancloud/ChatKit-OC,wizardguy/ChatKit-OC,Maru-zhang/ChatKit-OC