Update CONTRIBUTING.md
Update CONTRIBUTING.md

Fix some formatting.
VioletLife/CefSharp,VioletLife/CefSharp,Livit/CefSharp,VioletLife/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,dga711/CefSharp,Livit/CefSharp,dga711/CefSharp,dga711/CefSharp,jamespearce2006/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,VioletLife/CefSharp,Livit/CefSharp,dga711/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,Livit/CefSharp