Add feature for Crystal

[Caesarovich]

What type of PR is this?

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

Related Issues

None

Description

Hi, I'm hoping to include my feature collection to the index as it seems there's isn't any existing feature for the Crystal language.

Collection checklist

If your PR contributes a new collection, please utilize this checklist:

• Collection name
• Maintainer name
• Maintainer contact link (i.e. link to a GitHub repo, email)
• Repository URL
• OCI Reference
• I acknowledge that this collection provides new functionality, distinct from the existing collections part of this index.

[samruddhikhandale]

Thank you ⚡