Add enum to namespace toc

Author: adriendupuis

tools/php_api_ref/.phpdoc/template/components/table-of-contents.html.twig

@@ -52,10 +52,13 @@
 {% if node.traits[0] is defined %}
     {% set joined_data = joined_data|merge(node.traits) %}
 {% endif %}
+{% if node.enums[0] is defined %}
+    {% set joined_data = joined_data|merge(node.enums) %}
+{% endif %}
 
 {% if joined_data is not empty %}
     <h2 id="interfaces">
-        Interfaces, classes, and traits
+        Interfaces, classes, traits, and enums
         {%- include 'components/anchor.html.twig' with { anchor_link: link(node) ~ '#interfaces' } -%}
     </h2>
     <ul class="namespace-list">