Issue #3293814 by Spokje, quietone, catch: Move RDF-related help-topics to RDF module

core/modules/help_topics/help_topics/core.content_structure.html.twig

@@ -39,7 +39,7 @@ top_level: true
   <li>{% trans %}The core Node, Comment, Custom Block, Custom Menu Links, User, File, Image, Media, Taxonomy, and Contact modules all provide content entity types.{% endtrans %}</li>
   <li>{% trans %}The core Field UI module provides a user interface for managing fields and their display on entities.{% endtrans %}</li>
   <li>{% trans %}The core Layout Builder module provides a more flexible user interface for configuring the display of entities.{% endtrans %}</li>
-  <li>{% trans %}The core Filter, RDF, Responsive Image, and Path modules provide settings and display options for entities and fields.{% endtrans %}</li>
+  <li>{% trans %}The core Filter, Responsive Image, and Path modules provide settings and display options for entities and fields.{% endtrans %}</li>
 </ul>
 <p>{% trans %}Depending on the core and contributed modules that you currently have installed on your site, the related topics below, and other topics listed on the main <a href="{{ help_url }}">Help page</a>, will help you with tasks related to content structure.{% endtrans %}</p>
 <h2>{% trans %}Additional resources{% endtrans %}</h2>

core/modules/help_topics/help_topics/core.web_services.html.twig

@@ -26,8 +26,6 @@ related:
   <dd>{% trans %}Adds support for serializing content entities using the JSON version of HAL.{% endtrans %}</dd>
   <dt>{% trans %}HTTP Basic Authentication module{% endtrans %}</dt>
   <dd>{% trans %}Provides a way for web services to be authenticated using HTTP Basic authentication against Drupal user accounts.{% endtrans %}</dd>
-  <dt>{% trans %}RDF module{% endtrans %}</dt>
-  <dd>{% trans %}Enriches your content with metadata to let other applications (e.g., search engines, aggregators, and so on) better understand its relationships and attributes. This semantically enriched, machine-readable output for your website uses the <a href="http://www.w3.org/TR/xhtml-rdfa-primer/">RDFa specification</a>, which allows RDF data to be embedded in HTML markup.{% endtrans %}</dd>
 </dl>
 <p>{% trans %}There are also contributed modules that provide web services.{% endtrans %}</p>
 <h2>{% trans %}Additional resources{% endtrans %}</h2>

core/modules/rdf/help_topics/rdf.rdf.html.twig

@@ -0,0 +1,9 @@
+---
+label: 'Resource Description Framework (RDF)'
+top_level: true
+related:
+  - core.web_services
+---
+<h2>{% trans %}RDF module{% endtrans %}</h2>
+<p>{% trans %}Enriches your content with metadata to let other applications (e.g., search engines, aggregators, and so on) better understand its relationships and attributes. This semantically enriched, machine-readable output for your website uses the <a href="https://www.w3.org/TR/xhtml-rdfa-primer/">RDFa specification</a>, which allows RDF data to be embedded in HTML markup.{% endtrans %}</p>
+