docs: add AddDefaultAuthorizerToCorsPreflight property

Author: adanilev

versions/2016-10-31.md

@@ -792,12 +792,13 @@ Cors:
 Configure Auth on APIs. 
 
 **Authorizers:**
-Define Lambda and Cognito `Authorizers` and specify a `DefaultAuthorizer`. If you use IAM permission, only specify `AWS_IAM` to a `DefaultAuthorizer`. For more information, see the documentation on [Lambda Authorizers](https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-use-lambda-authorizer.html) and [Amazon Cognito User Pool Authorizers](https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-integrate-with-cognito.html) and [IAM Permissions](https://docs.aws.amazon.com/apigateway/latest/developerguide/permissions.html).  
+Define Lambda and Cognito `Authorizers` and specify a `DefaultAuthorizer`. If you use IAM permission, only specify `AWS_IAM` to a `DefaultAuthorizer`. For more information, see the documentation on [Lambda Authorizers](https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-use-lambda-authorizer.html) and [Amazon Cognito User Pool Authorizers](https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-integrate-with-cognito.html) and [IAM Permissions](https://docs.aws.amazon.com/apigateway/latest/developerguide/permissions.html).
 
 ```yaml
 Auth:
   ApiKeyRequired: true # OPTIONAL
   DefaultAuthorizer: MyCognitoAuth # OPTIONAL, if you use IAM permissions, specify AWS_IAM.
+  AddDefaultAuthorizerToCorsPreflight: false # OPTIONAL; Default: true
   # For AWS_IAM:
   # DefaultAuthorizer: AWS_IAM
   # InvokeRole: NONE # CALLER_CREDENTIALS by default unless overridden