use regional domain name for s3 bucket in cf distribution

Author: Ilya-Valasiuk

serverless.yml

@@ -69,7 +69,7 @@ resources:
       Properties:
         DistributionConfig:
           Origins:
-            - DomainName: ${self:custom.s3BucketName}.s3.amazonaws.com
+            - DomainName: !GetAtt WebAppS3Bucket.RegionalDomainName
               ## An identifier for the origin which must be unique within the distribution
               Id: myS3Origin
               ## In case you don't want to restrict the bucket access use CustomOriginConfig and remove S3OriginConfig