Use em instead of i and strong instead of b

They are semantically more correct

Signed-off-by: XhmikosR <xhmikosr@gmail.com>

scripts/js/settings-dns-records.js

@@ -264,5 +264,7 @@ $(document).ready(function () {
   });
 
   // Add a small legend below the CNAME table
-  $("#cnameRecords-Table").after("<small>* <b>TTL</b> in seconds <i>(optional)</i></small>");
+  $("#cnameRecords-Table").after(
+    "<small>* <strong>TTL</strong> in seconds <em>(optional)</em></small>"
+  );
 });