feat(apidoc): add /diagrams/ prefix to template

templates/apidoc.tmpl

@@ -8,6 +8,6 @@ Node classes list of {{ pvd }} provider.
 ## {{ pvd }}.{{ typ }}
 {% for class in classes %}
 
-<img width="30" src="/img/{{ class['resource_path'] }}" alt="{{ class['name'] }}" style="float: left; padding-right: 5px;" >
+<img width="30" src="/diagrams/img/{{ class['resource_path'] }}" alt="{{ class['name'] }}" style="float: left; padding-right: 5px;" >
 **diagrams.{{ pvd }}.{{ typ }}.{{ class['name'] }}**{% if class['alias'] %}, **{{ class['alias'] }}** (alias){% endif %}{% endfor %}
 {% endfor %}