Add docker support

[JackGilmore]

Description

Replicating https://github.com/timwis/jkan/pull/192 in our own instance of JKAN to allow people to run the project using Docker. Updated to Jekyll 4 as part of this change.

Motivation and Context

Should make it easier to run the project without having to mess around with installing Ruby and dependencies. Keeps the environment consistent (hopefully)

How Has This Been Tested?

Reviewed the PR for the original JKAN and it worked there. Applied the same changes to our repo and it works when running docker compose up. See screenshot below.

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [X] My code follows the code style of this project.
• [X] My change requires a change to the documentation.
• [X] I have updated the documentation accordingly.
• [X] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[KarenJewell]

Works on my machine!

[KarenJewell]

Added wiki page for running JKAN locally https://github.com/OpenDataScotland/the_od_bods/wiki/How-to:-Run-frontend-locally

Note first run of docker takes a while, subsequent runs are quicker.