Add PR 2054 to changelog
### SDK Features
### SDK Enhancements
+* `service/dynamodb/dynamodbattribute`: Add support for custom struct tag keys([#2054](https://github.com/aws/aws-sdk-go/pull/2054))
+ * Adds support for (un)marshaling Go types using custom struct tag keys. The new `MarshalOptions.TagKey` allows the user to specify the tag key to use when (un)marshaling struct fields. Adds support for struct tags such as `yaml`, `toml`, etc. Support for these keys are in name only, and require the tag value format and values to be supported by the package's Marshalers.
### SDK Bugs
* `aws/endpoints`: Add workaround for AWS China Application Autoscaling ([#2080](https://github.com/aws/aws-sdk-go/pull/2080))
