docs: remove version from download link (#21)

Author: bertonha

src/pages/index.js

@@ -21,7 +21,7 @@ const IndexPage = () => (
         Get Started
       </a>
       <a className="button" href="https://pypi.python.org/pypi/graphene">
-        Download 2.1
+        Download
       </a>
     </div>