[py] docs: added example for Virtual Authenticator

[SinghHrmn]

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Description

Added python example file for Virtual Authenticator. Depends on #1015

Motivation and Context

Types of changes

• [ ] Change to the site (I have double-checked the Netlify deployment, and my changes look good)
• [x] Code example file added
• [ ] Improved translation
• [ ] Added new translation (and I also added a notice to each document missing translation)

Checklist

• [x] I have read the contributing document.
• [x] I have used hugo to render the site/docs locally and I am sure it works.

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