Outdated example in readme

[gas1cent]

Hey there, thanks for maintaining the fork!

I've tried to use it and ran into an issue that can be solved with a small update to the readme. It currently states that the config should look like this:

plugins:
  - serverless-dynamodb
  - serverless-offline

custom:
  serverless-dynamodb:
    port: 8000
    docker: false

But in this case setting docker to true has no effect at all, and running sls offline start thrown an error saying Java is not in the path.

What helped me was modifying the custom part to:

custom:
  serverless-dynamodb:
    start:
      docker: true

With this new configuration everything works perfectly fine.

[domdomegg]

Thanks for reporting! I've addressed this in #46