docs(framework) Update Quickstart Tutorial documentation for TensorFlow with Flower Next

[chongshenng]

Issue

Description

The existing Quickstart Tutorial for TensorFlow at docs/framework uses pre-1.8 Flower commands.

Related issues/PRs

N/A

Proposal

Explanation

Update the Quickstart Tutorial for TensorFlow using Flower 1.8 commands. Revise text to improve readability.

Checklist

• [X] Implement proposed change
• ~~[ ] Write tests~~
• [X] Update documentation
• [X] Update the changelog entry below
• [X] Make CI checks pass

Changelog entry

Update Quickstart Tutorial documentation for TensorFlow with Flower Next.

Any other comments?

N/A