Create README.md
Create README.md

This is part off this change in serverless-webpack: elastic-coders/serverless-webpack#131
Explain how to work with the serverless-offline, serverless-webpack and serverless-dynamodb-local
dherault/serverless-offline,dherault/serverless-offline,dherault/serverless-offline,dherault/serverless-offline,dherault/serverless-offline,dherault/serverless-offline,dherault/serverless-offline