Update README download links to v2.1.1.
Update README download links to v2.1.1.

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