docs: In top index fix machine module link for the WiPy.

docs/topindex.html

@@ -43,7 +43,11 @@
       {% endif %}
       <p class="biglink">
         <a class="biglink" href="{{ pathto("library/index") }}">Library Reference</a><br/>
-        <span class="linkdescr">MicroPython libraries, including the <a href="{{ pathto("library/pyb") }}">pyb module</a></span>
+        {% if port == "wipy" %}
+          <span class="linkdescr">MicroPython libraries, including the <a href="{{ pathto("library/machine") }}">machine module</a></span>
+        {% else %}
+          <span class="linkdescr">MicroPython libraries, including the <a href="{{ pathto("library/pyb") }}">pyb module</a></span>
+        {% endif %}
       </p>
     </td>
     <td width="40%" style="padding-left:2em;">