Updated ReadMe and docker file

[gurashish1singh]

This is a short PR which:

• Updated the Readme for docker usage -> instead of $(pwd)/code changed it to ./code. $(pwd) gave me an error while running the command on powershell
• Updated the Dockerfile to copy over the local directory to /code before assigning the working dir to /code

[gurashish1singh]

@gaborvecsei I can't add you as a reviewer so pinging you here.