scilab: add link in 'Other resources' section

Doc/Manual/Scilab.html

@@ -1955,5 +1955,6 @@ <H2><a name="Scilab_other_resources"></a>37.6 Other resources</H2>
 <li>Example use cases can be found in the <tt>Examples/scilab</tt> directory.</li>
 <li>The test suite in the <tt>Examples/test-suite/scilab</tt> can be another source of useful use cases.</li>
 <li>The <a href="http://help.scilab.org/docs/5.5.0/en_US/api_scilab.html">Scilab API</a> is used in the generated code and is a useful reference when examining the output.</li>
+<li>This <a href="http://wiki.scilab.org/howto/Create%20a%20toolbox">guide</a> describes the Scilab external modules structure and files, in particular the files that are generated by SWIG for Scilab.</li>
 </ul>