Update to repository URL in README.rst file.
Update to repository URL in README.rst file.

Old URL made a reference to the previous repository location. While valid (via a redirect), it is no longer current.
crunchr/silk,Alkalit/silk,crunchr/silk,jazzband/silk,mtford90/silk,django-silk/silk,django-silk/silk,Alkalit/silk,crunchr/silk,jazzband/silk,mtford90/silk,mtford90/silk,jazzband/silk,django-silk/silk,crunchr/silk,django-silk/silk,Alkalit/silk,mtford90/silk,jazzband/silk