chore: add docs .tar.gz to the release

[dcarp]

No description provided.

[Copilot]

Pull Request Overview

This PR adds generated API documentation as a compressed archive to the release process. The change enables automatic inclusion of Starlark documentation files in releases to support Bazel Central Registry requirements.

• Adds documentation generation and packaging to the release preparation script
• Updates the BCR source template to include a docs_url field pointing to the generated documentation archive

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/workflows/release_prep.sh	Adds logic to generate and package API docs using Bazel queries and tar compression
.bcr/source.template.json	Adds docs_url field to specify the location of the documentation archive in releases

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