Fix ElasticsearchHttpPostPolicy

[shakirjames]

Description of changes:
Added /* to resource to fix Unauthorized error for es:ESHttpPost action.

Description of how you validated changes:

Created a custom policy and tested to remove unauthorized error.

        Policies:
          - Statement:
            - Effect: Allow
              Action:
                - es:ESHttpPost
              Resource: !Sub 'arn:aws:es:${AWS::Region}:${AWS::AccountId}:domain/${DomainName}/*'
          # NOTE: Fails to work missing "/*"
          #- ElasticsearchHttpPostPolicy: 
          #    DomainName: !Ref DomainName

Checklist:

• Write/update tests
• make pr passes
• Update documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[villasv]

You'll probably need to change some texts that depend on the previous behavior output.

[jlhood]

Thanks for contributing this fix!