Added CloudFormation code examples (#517)

* Added CloudFormation code examples

* Updated CloudFormation create-stack example based on feedback

* Updated CloudFormation describe-stack example based on feedback

* Removed extra line breaks in Cargo.toml file and orphaned comments in CloudFormation create-stack example

* Clarified how we get stack status in CloudFormation describe-stack example

* Updated CloudFormation code examples to follow latest code guidelines and proper service naming

Co-authored-by: Russell Cohen <rcoh@amazon.com>