Added Dutch translation

[Vistaus]

🙂

[Flaburgan]

Hello, thank you very much for contributing!

There is a bit more work to be done to have Dutch translations in the application, you translated the strings of the interface, but there is also the data. You need to go to https://github.com/Flaburgan/disco2very/tree/master/data/ademe and add a new nl folder where you should copy paste the content of the en folder and translate manually the strings.
You have to do this inside the 0-categories.json and footprintDetailCategories.json files as well, adding the key there.

Thanks!