Fix #330: Markdown changelog links (#333)

Fix links in the download page template and in one blog post to link to changelog.md rather than changelog.txt for versions released after this change was made in OpenTTD.

Author: merni-ns

_layouts/download.html

@@ -34,7 +34,13 @@ <h3>Download {{ page.name }}</h3>
         <div class="content">
             <p>Latest {{ page.name }} release in {{ page.category }} is {{ page.version }}, released on {{ page.date | date: "%Y-%m-%d %H:%M" }} UTC.</p>
 
+            {% assign markdowndate = '2024-10-22' | date: '%s' %}
+            {% assign versiondate = page.date | date: '%s' %}
+            {% if versiondate > markdowndate && raw_type contains "openttd" %}
+            <div class="changelog">[&nbsp;<a href="https://cdn.openttd.org/{{ folder }}/changelog.md">Changelog</a>&nbsp;]</div>
+            {% else %}
             <div class="changelog">[&nbsp;<a href="https://cdn.openttd.org/{{ folder }}/changelog.txt">Changelog</a>&nbsp;]</div>
+            {% endif %}
             <div id="download-combo">
                 <input type="hidden" id="download-combo-state" value="" />
                 <input type="hidden" id="download-base-name" value="{{ page.base }}" />