add link to how-to to Py HMAC page

Author: meihDS

app/templates/example_info.html

@@ -21,6 +21,10 @@ <h4>{{ title }}</h4>
     {% endfor %}
 {% endif %}
 
+{% if example["LinkToHowTo"] | length > 0 %}
+    <a target='_blank' href="{{ example['LinkToHowTo']['Path'] }}">{{ example['LinkToHowTo']['PathName'] }}</a>
+{% endif %}
+
 <p>
     View source file <a target="_blank" href="{{ source_url | safe }}">{{ source_file }}</a> on GitHub.
 </p>