Package tarball guide placeholder.

The authoritative shared guides live at the monorepo root in `guides/`.
Start the lifecycle story with
[`guides/flows/flag-lifecycle.md`](../../guides/flows/flag-lifecycle.md), which
teaches the canonical flag flow from birth to retirement.

Package-local readers usually want one of these next:

- [Getting Started](../../guides/introduction/getting-started.md)
- [Evaluation](../../guides/flows/evaluation.md)
- [Testing](../../guides/recipes/testing.md)