Include instructions on contributing to website

[Aariq]

The README and/or CONTRIBUTING.md are missing guidance on how to add content to and build the website hosted in this repo. Would be nice to have example code to preview it locally so that people could test their contributions.

[Gchism94]

Good call.

[Aariq]

Now that this is a Quarto website, feel free to copy whatever from here: https://cct-datascience.github.io/group-procedures/contributing.html