Improve semantic HTML tag usage on content pages

layouts/_partials/share.html

@@ -1,4 +1,4 @@
-<div class="share-buttons">
+<section class="share-buttons">
     {{ if .Site.Params.shareButtons.twitter }}
         <a class="twitter-share"
            target="_blank"
@@ -66,4 +66,4 @@
             {{- partial "icon.html" "printer" -}}
         </a>
     {{ end }}
-</div>
+</section>