removing symlink.  Adding contributing guidelines back (#3450)
removing symlink.  Adding contributing guidelines back (#3450)

* removing symlink.  Adding contributing guidelines back

* clean up

twitter/heron,twitter/heron,huijunwu/heron,huijunwu/heron,huijunwu/heron,twitter/heron,twitter/heron,twitter/heron,twitter/heron,twitter/heron,huijunwu/heron,twitter/heron,huijunwu/heron,huijunwu/heron,huijunwu/heron,huijunwu/heron