Line-wrapping, auto-formatting and pre-commit hooks

[sadielbartholomew]

1. Resolve #46 (see commits e6c10d5 and fd0bc2e) and resolve #47 (see first two commits and a trivial change in 92649e1).
2. In the process, add a black configuration file (d3df227) and configure pre-commit hooks, which all pass at the final commit of this PR, to enforce the same formatting at commit time (9ccaf6c).
3. When formatting the line-wrapping I barely looked at the text and yet I noticed a property description which was trivially wrong and in a confusing way, so I fixed that: see e0cc2e9.

[sadielbartholomew]

@davidhassell, though most of this is trivial, you may wish to cast an eye over the manual part, the line-wrapping (commit fd0bc2e), in case I made any mistakes (just needs if anything eyeballing to check the wrapped lines end with a whitespace), and e0cc2e9 because even though it is a trivial and non-controversial change, that is one which changes the CIM (but in a very minor way).

[sadielbartholomew]

I am thinking I might add a basic GitHub Action to confirm the auto-formatting has been applied by running the pre-commit hooks in a workflow job. Will push a further commit to add that now.

[sadielbartholomew]

Seeing if I can trigger the Actions job initially via open-close, though it may be that this PR needs to be merged before it will recognise the Actions workflow and not tell us that CI "has not been set up" as shown above...

[davidhassell]

Just eye-balled https://github.com/ES-DOC/esdoc-cim-v2-schema/commit/fd0bc2ec3a54c9b626e3958d6024161c501c36a7 and https://github.com/ES-DOC/esdoc-cim-v2-schema/commit/e0cc2e94278d72e9172629b17ee36ea2fe223221 - both look good to me.

[sadielbartholomew]

Thanks @davidhassell, in that case I will merge this and tag version 2.2!