Add link to the client certificate generator

Fixes https://bugs.cacert.org/view.php?id=1555

index.html

@@ -55,6 +55,14 @@
             </div>
           </div>
         </div>
+        <div class="card">
+          <div class="content">
+            <div class="header"><i class="certificate icon"></i> Client Certificate Generator</div>
+            <div class="description">
+              <p>The <a href="https://community.cacert.org/clientcert/">Client Certificate Generator</a> makes it possible to create client certificates directly in th browser in six simple steps.</p>
+            </div>
+          </div>
+        </div>
         <div class="card">
           <div class="content">
             <div class="header"><i class="brain icon"></i> CAcert Wiki</div>