docs: Link to CFFI from readme

README.rst

@@ -9,11 +9,12 @@ With pyspotify you can access music metadata, search in Spotify's library of
 20+ million tracks, manage your Spotify playlists, and play music from
 Spotify. All from your own Python applications.
 
-pyspotify use CFFI to make a pure Python wrapper around the official
-`libspotify <https://developer.spotify.com/technologies/libspotify/>`__
-library. It works on CPython 2.7 and 3.2+, as well as PyPy 2.6+ and PyPy3 2.6+.
-It is known to work on Linux and OS X. Windows support should be possible, but
-is awaiting a contributor with the interest and knowledge to maintain it.
+pyspotify use `CFFI <https://cffi.readthedocs.org/>`_ to make a pure Python
+wrapper around the official `libspotify
+<https://developer.spotify.com/technologies/libspotify/>`__ library. It works
+on CPython 2.7 and 3.2+, as well as PyPy 2.6+ and PyPy3 2.6+.  It is known to
+work on Linux and OS X. Windows support should be possible, but is awaiting a
+contributor with the interest and knowledge to maintain it.
 
 
 Project resources