Add some in-situ documentation to pre commit config

[tjdcs]

This helps me see what the current pre-commit config tools are when I happen to need to look at this again in several months.

‼️ Ahead of PR #1320

[coveralls]

coverage: 97.471%. remained the same
when pulling affff94 on docs/pre-commit
into 87ea299 on develop.

[KelSolaar]

We are running more hooks than this list, technically:

• check-added-large-files
• check-case-conflict
• check-merge-conflict
• check-symlinks
• check-yaml
• debug-statements
• end-of-file-fixer
• mixed-line-ending
• name-tests-test
• requirements-txt-fixer
• trailing-whitespace
• codespell
• isort
• ruff-format
• ruff
• blacken-docs
• prettier
• rst-backticks
• rst-directive-colons
• rst-inline-touching-normal

I'm not super excited by this because we have that configuration in all the repositories that we distribute on Pypi and if we change it here, we need to change it consistently with the other ones so that patching is easier:

• https://github.com/colour-science/colour-demosaicing/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-hdri/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-datasets/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-checker-detection/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-visuals/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-demosaicing/blob/develop/.pre-commit-config.yaml
• https://github.com/colour-science/colour-science.org/blob/master/.pre-commit-config.yaml

and I might have forgotten a few others.

This is generally true for most of our config files, if we do one change, we likely want to propagate it to all the other repositories.