Add link to CreateCustomForm topic.

whatsnew.htm

@@ -48,7 +48,7 @@ For conditions of distribution and use, see <a href="files/is/license.txt">LICEN
 
 <ul>
   <li>Added new [Setup] section directive <tt>WizardImageOpacity</tt> to specify the opacity of wizard images. This is useful if you want to use single wizard images for both light and dark appearances. For example, you can set it to <tt>150</tt> to achieve partial transparency. Defaults to fully opaque (non-transparent).</li>
-  <li><i>Documentation fix:</i> The prototype of Pascal Scripting support function <tt>CreateCustomForm</tt> was changed in the previous version, but the documentation was not updated accordingly. This has now been corrected.</li>
+  <li><i>Documentation fix:</i> The prototype of Pascal Scripting support function <tt>CreateCustomForm</tt> was changed in the previous version, but <a href="https://jrsoftware.org/ishelp/index.php?topic=isxfunc_createcustomform">its documentation</a> was not updated accordingly. This has now been corrected.</li>
   <li>Other minor improvements.</li>
 </ul>