You can add one External Menu Link that leads to another website. This is a great way to link to a blog, for example.   The External Menu Link, by default, will always be the link on the far right of the Menu List.  

You can add this feature under App Details

The box for the External Menu Link is below the Description box. 

1. Add a Name for the External Menu Link by replacing the words "New Link"

2. Add the url for the site you are linking to. You do not need to add https:// or http://

Blank Menu Link:

Filled out:

Site Menu:

Troubleshooting tips:

1. Check that the changes are published

2. Check that you have entered the url for the link (the menu button will not show with the url information).

3. Try refreshing your browser screen.