Merge pull request #71 from halindrome/patch-6

"Shown" is not inclusive enough

specs/paymentrequest.html

@@ -422,7 +422,7 @@ <h2>show()</h2>
         <p>
           The <code><dfn>show</dfn></code> method is called when the page wants to begin user interaction for the
           payment request. The <code>show</code> method will return a <a>Promise</a> that will be resolved when the
-          <a>user accepts the payment request</a>. Some kind of user interface will be shown to the user to facilitate the
+          <a>user accepts the payment request</a>. Some kind of user interface will be presented to the user to facilitate the
           payment request after the <code>show</code> method returns.
         </p>