Jekyll & theme update

[svrooij]

Upgrade documentation engine and devcontainer

Description

Jekyll was terribly old, this should upgrade it and also add a devcontainer

Your checklist for this pull request

🚨 Please review the guidelines for contributing to this repository.

• Make sure you are requesting to pull a topic/feature/bugfix branch (right side). Don't request your main!
• Make sure you are making a pull request against the main branch (left side). Also you should start your branch off svrooij/sonos-api-docs/main.
• Check your code additions will fail neither code linting checks nor unit test. (mine sometimes also fail, will probably ignore the lint failures)
• If you changed the documentation.json be sure to also regenerate the services files.
• The docs/services/index.md and the docs/services/*.md files should not be manually changed, only with the generator.

💔 Thank you!

[netlify]

✅ Deploy Preview for sonos-upnp ready!

Name	Link
🔨 Latest commit	d9957be
🔍 Latest deploy log	https://app.netlify.com/projects/sonos-upnp/deploys/6a4a737115cacfed1257729f
😎 Deploy Preview	https://deploy-preview-56--sonos-upnp.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.