Add a download card for use in articles

_includes/articles/outdated_notice.html

@@ -0,0 +1,19 @@
+{% unless page.no_outdated_notice %}
+{% unless page.categories contains "release" or page.categories contains "pre-release" or page.categories contains "showcase" %}
+{% comment %}
+`site.outdated_article_threshold` is generated by `_plugins/outdated_article_threshold.rb`.
+{% endcomment %}
+{% if page.date < site.outdated_article_threshold %}
+	<div class="card card-warning">
+		<p>
+		{% if page.outdated_notice_text %}
+			{{ page.outdated_notice_text }}
+		{% else %}
+			This article is from <strong>{{ page.date | date: "%B %Y" }}</strong>, some of its contents might be outdated and no longer accurate.<br>
+			You can find up-to-date information about the engine in the <a href="https://docs.godotengine.org/en/stable/">official documentation</a>.
+		{% endif %}
+		</p>
+	</div>
+{% endif %}
+{% endunless %}
+{% endunless %}