Semigroups. Monoids and Groups notebook tutorial.

[sasha704]

This is a pull request for the Semigroups, Monoids and Groups notebook tutorial.

[ozgurakgun]

Dear @ChrisJefferson @may1066

This is a reworking of your tutorial in the Conjure docs to use Jupyter notebooks. Thanks @sasha704!

The plan is to merge this into the documentation and keep it in additon to the version we already have there. Basically this makes your tutorial interactive - people can start a Google Colab VM with one click and run/edit/rerun the tutorial.

Any comments & feedback appreciated before we do the merge. Thanks!

[sasha704]

Here's the relevant link for the google colab: link

[ChrisJefferson]

Looks good!
This does make me think conjure might like some kind of nice pretty printer (printing out function (S,S) --> S doesn't look very nice), but that should not be part of this PR :)