layouts/_default/summary.html: Minor edit

Adjust post syntax to be the same as Bootstrap's blog example. We
apparently don't use a header anymore.

layouts/_default/summary.html

@@ -1,10 +1,8 @@
 {{ $dateFormat := default "Mon Jan 2, 2006" (index .Site.Params "date_format") }}
 
 <article class="blog-post">
-  <header>
     <h2 class="blog-post-title" dir="auto"><a href="{{ .Permalink }}">{{ .Title | markdownify }}</a></h2>
     <p class="blog-post-meta"><time {{ .Date.Format "2006-01-02T15:04:05Z07:00" | printf "datetime=%q" | safeHTMLAttr }}>{{ .Date.Format $dateFormat }}</time> by {{ .Params.author | default .Site.Params.author }}{{ if or (.Params.categories) (.Params.tags) }} in {{ partial "meta-terms.html" . }}{{ end }}</p>
-  </header>
   {{ .Summary }}
   <a href='{{ .Permalink }}'>Continue reading...</a>
 </article> <!-- /.blog-post -->