Enhance good practice note to point to SHOULD recommendation

index.html

@@ -830,8 +830,13 @@ <h4>Characters</h4>
             and that <code>&lt;head&gt;</code> element MUST have
             at least one <code>&lt;metadata&gt;</code> element child.</p>
 
-          <p class="note">It is good practice to locate all the <a>Character</a> objects within
-            a single <code>&lt;metadata&gt;</code> element parent.</p>
+          <p class="note"><a href="#character"></a> recommends that
+            all the <a>Character</a> objects be located within
+            a single <code>&lt;metadata&gt;</code> element parent,
+            and in the case that there are more than one
+            <code>&lt;metadata&gt;</code> element children of
+            the <code>&lt;head&gt;</code> element,
+            that the <a>Character</a> objects are located in the first such child.</p>
         </section>
 
         <section>