I would like to know whether there is an option to add custom tabs to the lightning navigation menu.
[SalesForce] How to add custom tabs to lightning navigation menu
Related Solutions
Actually figured it out. Indeed, the navigation menus has been deleted in Winter 17. Instead we will need to upgrade an app to a Lightning App where you will be able to set the Navigation Menus.
Setup Home>Apps>App Manager There is a drop down arrow to the right of each app, click edit. You can then select the object you would like to add tabs for each app.
Best Answer
In spring 16 release, salesforce lightning navigation customization has been supported. You can create a menu list and assign it to specified profiles.