Specify libyaml-dev requirement in CONTRIBUTING.md

[FiggyFoxFunc]

Hello,

I intend to contribute to your project. In doing so I have forked your project.
As I was running the bin/setup command I ran into an error installing the psych gem.
I found out eventually that libyaml-dev is a required dependency that is not preinstalled
on my linux distro, specifically Pop-OS.

I have managed to install the necessary gems now but an update specifying this for future would be great.
Thanks.

[JuanVqz]

Hey @FiggyFoxFunc it would be great if you open a PR adding a section in the contributing.md file, maybe something like so:

requirements

Pop-OS (or maybe linux)

which ruby version needs the libyaml-dev package.

command to install the libyaml-dev

Let me know if you have more questions.

[FiggyFoxFunc]

Hey,

Absolutely I will do that within the coming hours.

Thanks.

[FiggyFoxFunc]

I have made the pull request.

[JuanVqz]

I have made the pull request.

For some reason I missed the notification, but checking it now!