Bigger and bold title for issue/mr show pages

app/assets/stylesheets/sections/issues.scss

@@ -171,9 +171,9 @@ form.edit-issue {
   }
 }
 
-h3.issue-title {
+h2.issue-title {
   margin-top: 0;
-  font-size: 2em;
+  font-weight: bold;
 }
 
 .context .select2-container {

app/views/projects/issues/show.html.haml

@@ -26,7 +26,7 @@
             Edit
 
     %hr
-    %h3.issue-title
+    %h2.issue-title
       = gfm escape_once(@issue.title)
     %div
       - if @issue.description.present?

app/views/projects/merge_requests/show/_mr_box.html.haml

-%h3.issue-title
+%h2.issue-title
   = gfm escape_once(@merge_request.title)
 
 %div