firmware: remove dot, restores translation and looks better

src/www/widgets/widgets/system_information.widget.php

@@ -167,7 +167,7 @@ require_once("system.inc");
     <tr>
       <td><?= gettext('Updates') ?></td>
       <td>
-        <a href='/ui/core/firmware/#checkupdate'><?= gettext('Click to check for updates.') ?></a>
+        <a href='/ui/core/firmware/#checkupdate'><?= gettext('Click to check for updates') ?></a>
       </td>
     </tr>
     <tr>