Update the README file to include the information the sim_vim_sig.py …

[Unique-Usman]

Describe the changes you have made in this PR

Added the information about sim_vim_sig.py and how to run the script.

A clear and concise description of what you want to happen

Checklist

• [x] Self-review of changed code
• [x] Added automated tests where applicable
• [x] Update Docs & Guides

[Unique-Usman]

@etpeterson I added instruction on how to run sim_vim_sig.py for clearity.