Add date

inst/bulma/bulma.html

@@ -63,7 +63,10 @@ $if(title)$
 <h1 class="title is-1 toc-ignore">$title$</h1>
 $endif$
 $if(subtitle)$
-<h1 class="subtitle is-3 toc-ignore"><em>$subtitle$</em></h1>
+<h2 class="subtitle is-3 toc-ignore"><em>$subtitle$</em></h2>
+$endif$
+$if(date)$
+<h3 class="subtitle is-5 toc-ignore">$date$</h3>
 $endif$
 $if(header-links)$
 $for(header-links)$