Add Podman Support to README Instructions for Pipelines

[Tavernari]

This PR updates the README documentation for the Pipelines project to include instructions for running the project using Podman in addition to Docker.

Key Changes:

• Added Podman Instructions: Updated the README to provide equivalent podman commands alongside docker commands for running the Pipelines container.
• Networking Notes: Provided guidance on the use of host.containers.internal for Podman when specifying the API URL in Open WebUI, while retaining host.docker.internal for Docker.

These changes aim to improve flexibility for users who prefer Podman as their container runtime.

Changes made:

1. Updated Docker command sections with corresponding Podman commands:
   • Added podman run commands for launching the Pipelines container.
   • Provided relevant networking changes for Podman users.
2. Minor clarification added for troubleshooting Podman-specific networking issues.