Use better Mastodon illustrations

app/templates/mastodon/index.hbs

@@ -20,7 +20,7 @@
   </div>
   <div>
     <p class="illustration">
-      <img src="/img/undraw_connection_b38q.svg" alt="">
+      <img src="/img/undraw_connection_b38q-blue.svg" alt="">
     </p>
     <p>
       Every site is both its own community, as well as part of the global
@@ -42,7 +42,7 @@
   </div>
   <div>
     <p class="illustration">
-      <img src="/img/undraw_collab_8oes-blue.svg" alt="">
+      <img src="/img/undraw_filter_4kje-blue.svg" alt="">
     </p>
     <p>
       <strong>Curating your timeline and connections is easy</strong> and