Advices: some description about Middleware orders in the docs.

[me-v2]

in the docs, cann't find some detail about order of middleware .

[mawassk]

They will be executed in the order you add them. See implementation: https://github.com/encode/starlette/blob/master/starlette/applications.py

[skfarhat]

I think this detail is worth adding in the documentation. Indeed I thought it was the case that middleware is applied in order but couldn't find a reference, then came hunting in Github Issues :)