Fix up some HTML validation errors.

* Add a missing </nav> closing tag
* Remove a spurious </div> closing tag
* Add alt text for the WMF logo

Change-Id: I3db2a88f8598f82f6c4ceeef0c41f03086d03bdb
diff --git a/klaxon/templates/base.html b/klaxon/templates/base.html
index e135745..18a41ea 100644
--- a/klaxon/templates/base.html
+++ b/klaxon/templates/base.html
@@ -29,7 +29,7 @@
                 <div class="level-left">
                     <div class="level-item">
                         <a href="/">
-                            <img style="height: 5em;"
+                            <img alt="Wikimedia Foundation logo" style="height: 5em;"
                                 src="https://upload.wikimedia.org/wikipedia/commons/3/31/Wikimedia_Foundation_logo_-_vertical.svg">
                         </a>
                     </div>
diff --git a/klaxon/templates/index.html b/klaxon/templates/index.html
index bf7756b..d81bbf9 100644
--- a/klaxon/templates/index.html
+++ b/klaxon/templates/index.html
@@ -33,6 +33,7 @@
                         <span class="icon is-large is-clickable" onclick="fetchIncidents();">🔄</span>
                     </div>
                 </div>
+            </nav>
         </div>
         <div class="panel-block">
             <div class="container mb-2" id="incident_list">
@@ -42,7 +43,6 @@
             </div>
         </div>
     </nav>
-    </div>
 </section>
 <section class="section has-text-centered">
     <h2 class="title is-4">I need help!</h2>