Updated the footer link text

 Popmotion#956
it previously showing popmotion 8 in footer and after clicking to it the link takes you to the popmotion pure site  so it'll be more benificial for the users to keep it simple like as popmotion pure.

packages/site/components/template.js

@@ -126,7 +126,7 @@ export default function ({ children, tableOfContents }) {
                 <a href="/pose">Pose</a>
               </li>
               <li>
-                <a href="/pure">Popmotion 8</a>
+                <a href="/pure">Popmotion Pure</a>
               </li>
             </ul>
             <div>