Fix duplicate "when a" in section 3.1.

Fixes #112.

Author: gkellogg

index.html

@@ -770,7 +770,7 @@ <h2>The Context</h2>
       either be a simple string, mapping the <a>term</a> to an <a>IRI</a>,
       or a <a>dictionary</a>.</p>
 
-    <p>When a when a <a>member</a> with a <a>term</a> key has a <a>dictionary</a> value, the <a>dictionary</a> is called
+    <p>When a <a>member</a> with a <a>term</a> key has a <a>dictionary</a> value, the <a>dictionary</a> is called
       an <a>expanded term definition</a>. The example above specifies that
       the values of <code>image</code> and <code>homepage</code>, if they are
       strings, are to be interpreted as