Remove duplicate note about @context requirement.

Author: msporny

index.html

@@ -1288,10 +1288,7 @@ <h3>Contexts</h3>
 <a data-cite="JSON-LD11#the-context">JSON-LD Context</a>.
           </dd>
         </dl>
-        <p class="note">
-This specification requires a `@context` [=property=]
-to be present; this property is defined by [[JSON-LD11]].
-        </p>
+
         <pre class="example nohighlight" title="Usage of the @context property">
 {
   <span class="highlight">"@context": [