Remove redundant and obsolete build instructions wiki link.

download.phtml

@@ -40,7 +40,6 @@
   <ul class="imagelist">
     <li class="imagelistitem" style="background-image: url(<?=$top_dir?>/images/icons/package.png);"><a href="<?php echo $download_path.$latest_stable_source;?>">bzip2 compressed tarball</a> <?php printf (T_("for GnuCash %s"), $latest_stable)?></li>
   </ul>
-  <p><?php echo T_("For build instructions, please check the <span class=\"gnucash\">GnuCash</span> wiki which has <a href='https://wiki.gnucash.org/wiki/GnuCash#Installation'>guidelines for several distributions</a>.")?></p>
 
   <?php
     # Only show unstable download options if there really is an active unstable release