Adds entry to pending change log.
Adds PR to pending change log.
* Fixes [#2562](https://github.com/aws/aws-sdk-go/issues/2562), [#2411](https://github.com/aws/aws-sdk-go/issues/2411), [#2315](https://github.com/aws/aws-sdk-go/issues/2315)
### SDK Bugs
+* service/s3/s3manager: Fix uploader to check for empty part before max parts check (#2556)
+ * Fixes the S3 Upload manager's behavior for uploading exactly MaxUploadParts * PartSize to S3. The uploader would previously return an error after the full content was uploaded, because the assert on max upload parts was occurring before the check if there were any more parts to upload.
+ * Fixes [#2557](https://github.com/aws/aws-sdk-go/issues/2557)
