[Feat] Improve Installation Instructions

[buddha314]

Is your feature request related to a problem? Please describe.

There are several python a2a packages and most have individual installation instructions. This package should be specific. For instance, it appears the process is

Installation

• Clone this repo
• Enter the repo directory
• uv venv
• uv pip install .

Testing

• Linux: source .venv/bin/activate
• python
• > import a2a

Describe the solution you'd like

Please add these details (if correct) to the README.md file.

Code of Conduct

• I agree to follow this project's Code of Conduct

[kavinkumar807]

@holtskinner if this is valid for contribution, shall I check with this ?