docs: Alphabetise microbit module entries and use docstring notations.

[microbit-carlos]

Content hasn't changed and this will help reduce conflicts with upcoming rebase of the v2-docs branch which also needs to do more changes to this file.

[microbit-carlos]

As the docs are slowing adopting the :param :, :returns:, etc docstrings notation I've updated this PR to include those changes for the micro:bit module. I've also added some additional information to be a bit more complete.

[microbit-carlos]

@microbit-mark could you have a quick review once you get a chance?
@dpgeorge I assume this kind of updates are generally good to go into the docs without major reviews?

[microbit-carlos]

Review URL: https://microbit-micropython--734.org.readthedocs.build/en/734/microbit.html

[microbit-mark]

👍🏻 LGTM thanks @microbit-carlos