docs: adds a new post-deployment guide for users who have deployed using the AVM template

[Harsh-Microsoft]

Purpose

This pull request adds a new post-deployment guide for the AVM solution accelerator, providing clear instructions for configuring authentication, uploading documents, and accessing the chat application after deployment. The guide also links to advanced configuration options for further enhancements.

Documentation improvements:

• Added docs/AVMPostDeploymentGuide.md to provide step-by-step post-deployment instructions for users of the AVM Chat with your data solution accelerator, including authentication setup, admin site usage, and chat application access.
• Included references and links to advanced configuration guides for features such as image processing, vectorization, conversation flow customization, and speech-to-text integration.

Does this introduce a breaking change?

• Yes
• No

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

• ...

Other Information