title: AWS : register-container-instance - examples needed
body: <p>I am in process of registering EC2 instance to my ECS cluster. I am bot surprised that I can not add EC2 instance using graphical UI ( That is What my experience suggests, I could be wrong.) 
  Command line interface is very hard as there are no good examples. I tried to Google it. I think thi
  s very complex that it needs to be..</p>
  
  <p>I am running command,</p>
  
  <p>aws ecs register-container-instance  --cluster default 
  it needs --instance-identity-document and --instance-indentity-document-signature and few other arguments..I am able get document but some good example would help me further. Does anybody has same frustration ? Any advice</p>