Add a section to the contributor guide on project board & repo automation

[RayStick]

After the physiopy community has become more familar with using the project boards, and the labels & activities become more finalised, I am happy to add a section to the contributor guidelines on how to use it. We could also include a section on what other automation (workflows, github actions) happen across the repos in physiopy.

EDIT on 31st May

Some automation is already happening on the project board via: https://docs.github.com/en/issues/planning-and-tracking-with-projects/automating-your-project. It would be good to understand this better, so we can build upon it, and check the existing default settings regarding automation are what we want.

For example, when you close an Issue, it automatically gets moved to 'Done' on the Project Board. Does the same happen for a merged PR?

[RayStick]

@m-miedema do you think this Issue is in the wrong repo? We can move to another more appropriate one if so - one that talks about docs. I ask this because this issue refers to writing doumentation about the project board and the automations, not actually implementing them, if you see the distinction. So it might be a bit confusing that it is here!

[m-miedema]

It did confuse me a little bit when I was trying to understand the purpose of this repo. So, depending on where we land, it might be better to move this to the physiopy.github.io repo. However, if we end up creating a separate repo for the contributor's guide, it would move to that one! I think you can hold off until we make a decision there.