Should we add `pre-commit` to the `docs/requirements.txt` and to CONTRIBUTING.md?

[sfmig]

Is your feature request related to a problem? Please describe.
We are asking contributors to check they run the required pre-commits which is great, but the contribution guidelines do not mention the pre-commit installation.

Describe the solution you'd like
I think the easiest way would be:

• to add pre-commit to the docs/requirements.txt, and
• add a pre-commit install command in the CONTRIBUTING.md to install the provided hooks.

Maybe the Github workflow section could also be reorganised. I think I would have first the dependencies installation, next the "github workflow", and last the local build commands.

Describe alternatives you've considered
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Additional context
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[niksirbi]

It all sounds reasonable and you should go for it. I think that contributing guide was written before we added hooks etc, so we just forgot to update it.