Update the CONTRIBUTING.md file

### Feature Description

At minimum, we need to add JS docs to [CONTRIBUTING.md](https://github.com/JupiterBroadcasting/jupiterbroadcasting.com/blob/develop/CONTRIBUTING.md).

Having someone new, especially who doesn't have very much technical or hugo/web-dev experience ensure that all the steps and general guidance in that doc is useful (giving some type of feedback probably on this issue or on their PR), would probably help ensure it's well documented from a new person perspective.

I'd imagine some documentation around the testing stuff would be helpful as well. @TheHesster had expressed some potential interest in this part (tests), so if you'd like to tackle that, that'd be awesome (no pressure though if you don't want to).

### Reference to Feature

* [Mention of adding JS location to docs](https://matrix.to/#/!rDlEtonuSythLzmxQL:jupiterbroadcasting.com/$ukUhoSh_tFeDxWvWWycRH1NsMiDjQTqlG0o-DE7oIwI)
* [TheHesster expressing interest](https://matrix.to/#/!rDlEtonuSythLzmxQL:jupiterbroadcasting.com/$dI3jbuYyWq8yz7y-d--1uSfrYvdeb_2_I0p3er4mFSQ)