Merge branch '15606-discussion-styling' into 'master'

Increase screen width breakpoint for hide/show discussion

Closes #15606

See merge request !3915

app/assets/stylesheets/pages/notes.scss

@@ -215,7 +215,7 @@ ul.notes {
 }
 
 .discussion-actions {
-  @media (max-width: $screen-sm-max) {
+  @media (max-width: $screen-md-max) {
     float: none;
     margin-left: 0;