Setup Instructions and User Domain Class Documentation

[AWSandAzureandFullStackEngineer]

Setup Instructions and User Domain Class Documentation

This issue includes the following:

• Project setup instructions
• User domain class documentation, including purpose and field explanations
• Instructions for downloading, forking, and running the project on Mac, Windows, or Linux

Tasks:

• [x] Create README with setup instructions
• [x] Document User domain class in README with field explanations
• [x] Add instructions on cloning/forking and running the project on multiple OS

[AWSandAzureandFullStackEngineer]

Everything checks