Settings help text spacing fix

Update spacing of help texts for inputs and checkboxes
on settings pages

app/assets/stylesheets/pages/settings.scss

@@ -110,9 +110,14 @@
 
   .bs-callout,
   .form-check:first-child,
-  .form-text.text-muted {
+  .form-check .form-text.text-muted,
+  .form-check + .form-text.text-muted {
     margin-top: 0;
   }
+
+  .form-check .form-text.text-muted {
+    margin-bottom: $grid-size;
+  }
 }
 
 .settings-list-icon {