Improve 404 page slightly

Author: holly-cummins

src/partials/article-404.hbs

@@ -1,7 +1,8 @@
 <article class="doc">
 <h1 class="page">{{{or page.title 'Page Not Found'}}}</h1>
 <div class="paragraph">
-<p>The page you&#8217;re looking for does not exist. It may have been moved. You can{{#with site.homeUrl}} return to the <a href="{{{this}}}">start page</a>, or{{/with}} follow one of the links in the navigation to the left.</p>
+<p>The page you&#8217;re looking for does not exist. It may have been moved.
+  You can{{#with site.homeUrl}} return to the <a href="{{{this}}}">start page</a>, or{{/with}} browse the extensions in the navigation bar on the left.</p>
 </div>
 <div class="paragraph">
 <p>If you arrived on this page by clicking on a link, please notify the owner of the site that the link is broken.