Add `flower-simulation` to `ref-api-cli` docs

[chongshenng]

Issue

Description

The flower-simulation is not listed in ref-api-cli documentation.

Related issues/PRs

Related to #3382.

Proposal

Explanation

Add flower-simulation to ref-api-cli via sphinx-argparse.

Checklist

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

Changelog entry

Any other comments?

N/A