Add an interactive tutorial as a Jupyter notebook

[simonw]

Can show people how to open this up in Binder.

[simonw]

https://mybinder.org/v2/gh/simonw/sqlite-utils/main?filepath=docs%2Ftutorial.ipynb

[simonw]

OK, this works great as a proof-of-concept (though maybe I should remove the output from the cells so people have to run it themselves in the Binder environment?)

Next challenge: how extensive should it be? What features should I cover? Should I do a basic tutorial and then several advanced tutorials?