Add fourth page

src/components/section-head.html

@@ -5,7 +5,7 @@
 </script>
 <div class="section-header">
   <div>
-    <h1>{{header}}</h1>
+    <markdown># {{header}}</markdown>
   </div>
   <div>
     <yield></yield>

src/components/tab-content.html

@@ -13,6 +13,9 @@
   <button hx-get="/partials/interests.html" hx-push-url="/interests.html"
     class="{{ selected-- == 0 ? 'selected' : '' }}" role="tab" aria-selected="{{ selected == -1 ? 'true' : 'false' }}"
     aria-controls="tab-content">Our Interests</button>
+  <button hx-get="/partials/page_four.html" hx-push-url="/page_four.html"
+    class="{{ selected-- == 0 ? 'selected' : '' }}" role="tab" aria-selected="{{ selected == -1 ? 'true' : 'false' }}"
+    aria-controls="tab-content">Page Four</button>
 </nav>
 <hr style="margin: 0">
 <div id="tab-content" role="tabpanel" class="tab-content">