docs: add AI solution disclaimer

[Harmanpreet-Microsoft]

Added a disclaimer regarding AI solutions and associated risks.

Purpose

This pull request adds a disclaimer to the README.md to clarify user responsibility and compliance requirements when using the solution accelerator. This is an important update for transparency and legal compliance.

Documentation and compliance:

• Added a disclaimer about user responsibility for risk assessment and legal compliance when using AI solutions, with links to relevant transparency documents for Agent Service and Agent Framework.
• ...

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