Chat related: update latest links to unstable to avoid 404s

[jffortier]

Background

Replace links pointing to latest with unstable in the Chat component documentation to ensure that the correct version is referenced.

Same as https://github.com/Shopify/checkout-web/pull/39877

[github-actions]

We detected some changes in packages/*/package.json or packages/*/src, and there are no updates in the .changeset directory. If the changes are user-facing and should cause a version bump, run yarn changeset to track your changes and include them in the next release CHANGELOG. If you are making simple updates to repo configuration, examples, or documentation, you do not need to add a changeset.