Add pre-commit dependency in DEV group

[rragundez]

Currently the pre-commit dependency is set for the user to install on their own. This is unnecessary and has drawbacks:

• The mechanism to run the pre-commit hook is there when making a commit so it gets triggered but the user will encounter an error about pre-commit not being installed. Which is unexpected.
• Allowing the user to provide its own pre-commit dependency can lead to non-reproducible errors due to version mismatch. I have seen it enough time to know it will happen to people and normally these errors are quite obscure to find that it is a version error. You can endup with the situation that locally it passes but in the CI it does not.
• Having it as a dev dependency makes it much easier for the user and it just flows the way to use it.
• Documentation and startup guides are easier with a less step for setup (one less step where things can go wrong)

This PR simply adds the pre-commit dependency into the dev group and updated the documentation to reflect that

[rragundez]

There were some conflicts but now seems to be OK