Workshop 3 CloudFormation template validation fails on valid email domain.

[circuitousNerd]

The CloudFormation template for workshop 3 has the following validation for CognitoAdminEmail:

CognitoAdminEmail:
 Type: String
 Default: cognitoadmin@example.com
 AllowedPattern: '^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$'
 Description: Enter a valid email address to be used for Kibana Cognito authentication.

This will cause any valid TLD with a length > 3 (such as .limited) to fail.