docs: link Slackware to the latest SlackBuild

Author: trollixx

download.html

@@ -112,8 +112,8 @@ <h3 id="linux-opensuse">openSUSE</h3>
      class="btn btn-default" role="button">View openSUSE package</a>
 
   <h3 id="linux-slackware">Slackware</h3>
-  <p>A SlackBuild script is available for users of Slackware.</p>
-  <a href="https://slackbuilds.org/repository/14.2/development/zeal/"
+  <p>Build and install Zeal from SlackBuilds.org.</p>
+  <a href="https://slackbuilds.org/result/?search=zeal"
      class="btn btn-default" role="button">View SlackBuilds.org</a>
 
   <h3 id="linux-ubuntu">Ubuntu</h3>