Release v6.1.2

Assistant.describeFile now exposes includeUrl as an optional argument, and it will default to true if not provided. sourceCollection is also now exposed on CreateIndexServerlessSpec and IndexModel.

What's Changed

• Expose includeUrl in Assistant.describeFile, add sourceCollection for serverless by @austin-denoble in #349

Full Changelog: v6.1.1...v6.1.2