Description:
Create a new README file for the recently introduced buildah-ns Tekton task. The README should include:

• A brief overview of the buildah-ns task.

• Key differences between the existing buildah task and the new buildah-ns task (e.g., namespace support, additional features, behavioral changes).

• Usage examples and configuration details (if applicable).

• Any known limitations or compatibility notes.

This documentation will help users understand when and how to use the buildah-ns task over the standard buildah task.