fix: unpublishSafe docs url

lib/workers/branch/status-checks.js

-const { appSlug } = require('../../config/app-strings');
+const { appSlug, urls } = require('../../config/app-strings');
 
 module.exports = {
   setUnpublishable,
@@ -28,7 +28,7 @@ async function setUnpublishable(config) {
       context,
       description,
       state,
-      'https://renovatebot.com/docs/configuration-reference/configuration-options#unpublishsafe'
+      urls.documentation
     );
   }
 }