Links to external websites can be added to Menus inside of Releases.
To add a link to a Menu, open a Release and click on the Menu Tab and then the Add Menu Item button.
This will open fields to the right that allow for a label and link to be added.
First, click the Link radio box, which will open a field for a URL.
Next, add the label to be displayed in the menu in the top field. Then add the URL of the webpage the item should link to.
Click the Save button.
The item will now appear in the Menu Items list.
You can preview the item in the Menu from here by clicking the Preview button on the upper right of the interface.
When the Release opens, click the Menu button at the bottom left if it's not already open.
The new item will appear in the list that opens.
Read more about adding other types of Menu items to Releases: Release Menu