Change header text from 'Explore' to 'Join' (#949)

Author: jeswr

index.html

@@ -71,7 +71,7 @@ <h2 id="organisations_using_solid">Organisations using Solid</h2>
       <a href="/community">
         <div class="tile-header">
           <img alt="users icon" src="/assets/img/icon/users.svg" />
-          <h2 id="explore_the_community">Explore the community</h2>
+          <h2 id="explore_the_community">Join the community</h2>
         </div>
         <p>Connect with the community through forums, chats and at events, like Solid World.</p>
         <p class="tile-links-nav-hint">Solid community</p>