FEATURE: add category name in articleSection meta tag for schema. (#21004)

https://schema.org/DiscussionForumPosting

app/views/topics/show.html.erb

@@ -36,6 +36,9 @@
   <%- if include_crawler_content? %>
     <div itemscope itemtype='http://schema.org/DiscussionForumPosting'>
       <meta itemprop='headline' content='<%= @topic_view.title %>'>
+      <% if @topic_view.topic.category.present? %>
+        <meta itemprop='articleSection' content='<%= @topic_view.topic.category.name %>'>
+      <% end %>
       <meta itemprop='keywords' content='<%= @tags.map(&:name).join(', ') %>'>
       <div itemprop='publisher' itemscope itemtype="http://schema.org/Organization">
         <meta itemprop='name' content='<%= SiteSetting.company_name.presence || SiteSetting.title %>'>

spec/views/topics/show.html.erb_spec.rb

@@ -59,5 +59,6 @@ RSpec.describe "topics/show.html.erb" do
     topic_schema = doc.css('[itemtype="http://schema.org/DiscussionForumPosting"]')
     expect(topic_schema.size).to eq(1)
     expect(topic_schema.css('[itemtype="http://schema.org/Comment"]').size).to eq(2)
+    expect(topic_schema.css('[itemprop="articleSection"]')[0]["content"]).to eq(topic.category.name)
   end
 end