wg: Fix title hierarchy and duplicate ids

wg.html

@@ -78,10 +78,20 @@ <h3><a href="https://github.com/ircv3/ircv3-specifications/milestone/4">Roadmap<
       </div>
 
       {% for post in site.posts limit:10 %}
+      {% comment %} add a prefix to ids to avoid duplicates within the same page {% endcomment %}
+      {% assign h3_prefix = '<h3 id="' | append: post.id | append: '-' | replace_first: '/', '' %}
+      {% assign h4_prefix = '<h4 id="' | append: post.id | append: '-' | replace_first: '/', '' %}
+      {% assign h5_prefix = '<h5 id="' | append: post.id | append: '-' | replace_first: '/', '' %}
+      {% assign h6_prefix = '<h6 id="' | append: post.id | append: '-' | replace_first: '/', '' %}
       <div class="post">
           <h3><a href="{{ post.url }}">{{ post.title | xml_escape }}</a> <span class="meta">{{ post.date | date_to_string }}</span></h3>
           <div class="post-content">
-              {{ post.content }}
+               {{ post.content
+                | replace: '<h6 id="', h6_prefix
+                | replace: '<h5 id="', h5_prefix
+                | replace: '<h4 id="', h4_prefix
+                | replace: '<h3 id="', h3_prefix
+                }}
           </div>
       </div>
       {% endfor %}