Adopt @lexnederbragt suggestion for Edit link

https://github.com/swcarpentry/lesson-example/pull/104#issuecomment-283310978

_includes/lesson_footer.html

@@ -17,7 +17,7 @@
     </div>
     <div class="col-md-6" align="right">
       <h4>
-        <a href="{{site.github.repository_url}}/edit/gh-pages/{{page.path}}">Improve this page <span class="glyphicon glyphicon-pencil" aria-hidden="true"></span></a>
+	<a href="{{site.github.repository_url}}/edit/gh-pages/{{page.path}}">Edit on GitHub</a>
 	/
 	<a href="{{ site.github.repository_url }}/blob/gh-pages/CONTRIBUTING.md">Contributing</a>
 	/

_includes/navbar.html

@@ -76,7 +76,7 @@
 
 	{% comment %} Always show license. {% endcomment %}
         <li><a href="{{ page.root }}/license/">License</a></li>
-	<li><a href="{{site.github.repository_url}}/edit/gh-pages/{{page.path}}">Edit on GitHub</a></li>
+	<li><a href="{{site.github.repository_url}}/edit/gh-pages/{{page.path}}">Improve this page <span class="glyphicon glyphicon-pencil" aria-hidden="true"></span></a></li>
       </ul>
       <form class="navbar-form navbar-right" role="search" id="search" onsubmit="google_search(); return false;">
         <div class="form-group">