Add in-context examples

[aloctavodia]

All current examples are of the usage/api-explanation type. It would be nice to also have examples with more context, even if we use toy-examples.

[CodingWithError]

Hey can you give me a bit more information about this

[aloctavodia]

Library functionality should be explained in the context of (simple) examples resembling problems users may find in real data analysis problems.