Use h1 element for project title instead of div

Improves semantic HTML and SEO by using a proper heading element.

templates/project.html

@@ -5,7 +5,7 @@
 {%- endblock title -%}
 
 {%- block main -%}
-    <div class="title">{{ page.title }}</div>
+    <h1 class="title">{{ page.title }}</h1>
 
     <div class="links">
         <a href="https://github.com/uutils/{{page.title}}">Repository</a>