Rename environment variable controlling public docs build

Author: jeremystretch

docs/_theme/main.html

@@ -2,8 +2,8 @@
 
 {% block site_meta %}
   {{ super() }}
-  {# Disable search indexing unless we're building for ReadTheDocs #}
-  {% if not config.extra.readthedocs %}
+  {# Disable search indexing unless we're building for public consumption #}
+  {% if not config.extra.build_public %}
     <meta name="robots" content="noindex">
   {% endif %}
 {% endblock %}

mkdocs.yml

@@ -42,7 +42,7 @@ plugins:
             show_root_toc_entry: false
             show_source: false
 extra:
-  readthedocs: !ENV READTHEDOCS
+  build_public: !ENV BUILD_PUBLIC
   social:
     - icon: fontawesome/brands/github
       link: https://github.com/netbox-community/netbox