Fix some invalid HTML.

bin/template.html

@@ -37,7 +37,7 @@ $endfor$
 $if(title)$
 <header id="title-block-header">
 <a href="$rel-root$" title="Home">
-  <img src="$rel-root$/doc/Logos/gf1.svg" height="200px" class="float-md-right ml-3 mb-3 bg-white" alt="GF Logo">
+  <img src="$rel-root$/doc/Logos/gf1.svg" height="200" class="float-md-right ml-3 mb-3 bg-white" alt="GF Logo">
 </a>
 <h1 class="title">$title$</h1>
 $if(subtitle)$
@@ -100,8 +100,7 @@ $body$
       </div>
 
       <div class="col-6 col-sm-3">
-        <h6 class="text-muted">Contribute</i>
-        </h6>
+        <h6 class="text-muted">Contribute</h6>
         <ul class="list-unstyled">
           <li><a href="http://groups.google.com/group/gf-dev">Mailing List</a></li>
           <li><a href="https://github.com/GrammaticalFramework/gf-core/issues">Issue Tracker</a></li>
@@ -116,8 +115,8 @@ $body$
         <a href="https://github.com/GrammaticalFramework/gf-rgl">RGL</a> ·
         <a href="https://github.com/GrammaticalFramework/gf-contrib">Contributions</a>
       </div>
-    <div>
-  <div>
+    </div>
+  </div>
 </footer>
 $for(include-after)$
 $include-after$