Show informative text when opening app for the first time

As you see in the below screenshots, there is no information on how to get started after installing the app.

On the Manage folders section, there is a lot of unused white space which could be used to explain how it works. So we could add some text like, "To get started, tap the plus button to add a root." and maybe more text could be added to reduce the learning curve. The Navigate data section could also display some text on how to get started

Start by locating the UI for the Manage folders and Navigate data sections mentioned in the issue, then compare their current empty states with the screenshots. Done means both sections give newcomers clear guidance on how to get started.

Written by the indexing model from the issue text.