Remove untranslated string

Fixes #26

src/partials/dialog.about.html

@@ -16,7 +16,7 @@
                     <span translate>about.ALL_RIGHTS_RESERVED</span>
                 </p>
 
-                <p>Download the Threema app here: <a href="https://threema.ch/">https://threema.ch/</a></p>
+                <p><a href="https://threema.ch/">https://threema.ch/</a></p>
 
                 <h2>Open Source</h2>
                 <p translate>about.OPEN_SOURCE</p>