Add documentation page for CI integration

[anderseknert]

We currently provide an intro to using the GitHub Action here: https://github.com/StyraInc/regal#github-actions

I think it would be good to break that out into a separate page on the topic of CICD integration, where we could include GitLab, and possibly other build systems.

[Parsifal-M]

Hey! 👋

I will add some docs for using regal in Gitlab using the container image 👍

I could also add maybe some instructions by downloading the binary but I think the docker image will be the way forward for most 😅

Will pick this up tomorrow/friday ❤️

[anderseknert]

That's awesome @Parsifal-M 👍 Just create a new doc in the docs directory called cicd.md or something like that, and remember to add a link or two from the README :)

For GitHub, you could just copy some of the content from https://github.com/StyraInc/setup-regal