Use Netlify to build documentation preview for PRs

[st0012]

Motivation

Currently, to review a documentation change, one needs to:

1. Pull the change and checkout to it with gh command
2. Run cd jekyll
3. Run bundle exec jekyll serve

And it's assuming that Jekyll is already installed to the latest version locally.

If we can have a way to preview the doc changes directly, it'd be much easier for maintainers and anyone who's interested in the changes to review. And hopefully lowering the reviewing costs can also make doc contribution (feel) easier.

Implementation

1. Use Ruby 3.3.3 for jekyll folder. I explained more in the comments below.
2. Add netlify.toml to store all build configurations.

With the build ignore config in place, Netlify's free plan should cover our current usages.

Automated Tests

Manual Tests

[netlify[bot]]

✅ Deploy Preview for ruby-lsp ready!

Name	Link
🔨 Latest commit	ba4b2b0161c0e4d21b16843fbf044b9c277eb8a2
🔍 Latest deploy log	https://app.netlify.com/sites/ruby-lsp/deploys/66fc577306886c0008babe78
😎 Deploy Preview	https://deploy-preview-2646--ruby-lsp.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

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[github-actions[bot]]

This pull request is being marked as stale because there was no activity in the last 2 months

[st0012]

Since Netlify's usage at Shopify is still not approved, I'm closing this now.