DOC : added DOI link to citing.html

Author: tacaswell

doc/_templates/citing.html

@@ -24,4 +24,11 @@ <h1>Citing matplotlib</h1>
   year      = 2007
 }
 </pre>
+
+
+<h2>DOIs</h2>
+<dl>
+  <dt>v1.4.0</dt><dd><a href="http://dx.doi.org/10.5281/zenodo.11451"><img src="https://zenodo.org/badge/doi/10.5281/zenodo.11451.png" alt="10.5281/zenodo.11451"></a></dd>
+</dl>
+
 {% endblock %}