Update README - Required properties, Output

[asrindayananda]

After installing successfully and creating a CommandRunner command in Cloudformation with just the Command property I kept getting errors like Either the command failed to execute, the value written to /command-output.txt was invalid or the Subnet specified did not have internet access.

• I had to add Role and LogGroup properties as well. So I think these are required.
• Also output value of the command only worked when I changed it to CommandRunner, I guess it is looking for a resource name. Great plugin! Hope it becomes a standard Cloudformation Type

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[shantgup]

Thank you for your pull request, we appreciate your contribution.

Role and LogGroup are not required. Role is only required if your command is using the AWS CLI. LogGroup is only needed if you want to log the output.

And thank you so much, we are working towards making it a standard CloudFormation type.