Update contributing guidelines with a 64 character line length.
Update contributing guidelines with a 64 character line length.

tchiotludo/spfjs,tchiotludo/spfjs,tchiotludo/spfjs,nicksay/spfjs,youtube/spfjs,theanh/spfjs,nicksay/spfjs,scrapp-uk/spfjs,scrapp-uk/spfjs,theanh/spfjs,scrapp-uk/spfjs,youtube/spfjs,scrapp-uk/spfjs,scrapp-uk/spfjs,nicksay/spfjs,theanh/spfjs,youtube/spfjs,youtube/spfjs,nicksay/spfjs,theanh/spfjs,youtube/spfjs,tchiotludo/spfjs,theanh/spfjs,tchiotludo/spfjs,nicksay/spfjs