Fix link to in-depth guide on prebuilds article

[jasonmfehr]

What type of PR is this?

• [ ] Add a new dev container collection
• [ ] Update to an existing dev container collection
• [X] Documentation/spec update
• [ ] Other containers.dev site update (UX, layout, etc)

Related Issues

N/A

Description

Fixes a broken link. The original link pointed to a blog post, but that blog post was turned into a full article within the guide.

Collection checklist

N/A