Updates changelog for v0.26.0 release. (#829)

Author: jasdel

CHANGELOG.md

@@ -1,12 +1,20 @@
 # Release 2020-09-30
+
 ## Service Client Highlights
 * Service clients have been bumped to `v0.26.0` simplify the documentation experience when using [pkg.go.dev](https://pkg.go.dev/github.com/aws/aws-sdk-go-v2).
+* `service/s3`: Disable automatic decompression of getting Amazon S3 objects with the `Content-Encoding: gzip` metadata header. ([#748](https://github.com/aws/aws-sdk-go-v2/pull/748))
+  * This changes the SDK's default behavior with regard to making S3 API calls. The client will no longer automatically set the `Accept-Encoding` HTTP request header, nor will it automatically decompress the gzipped response when the `Content-Encoding: gzip` response header was received.
+  * If you'd like the client to sent the `Accept-Encoding: gzip` request header, you can add this header to the API operation method call with the [SetHeaderValue](https://pkg.go.dev/github.com/awslabs/smithy-go/transport/http#SetHeaderValue). middleware helper.
+* `service/cloudfront/sign`: Fix cloudfront example usage of SignWithPolicy ([#673](https://github.com/aws/aws-sdk-go-v2/pull/673))
+  * Fixes [#671](https://github.com/aws/aws-sdk-go-v2/issues/671) documentation typo by correcting the usage of `SignWithPolicy`.
+
 ## Core SDK Highlights
 * SDK core module released at `v0.26.0`
 * `config` module released at `v0.1.1`
 * `credentials` module released at `v0.1.1`
 * `ec2imds` module released at `v0.1.1`
 
+
 # Release 2020-09-28
 ## Announcements
 We’re happy to share the updated clients for the v0.25.0 preview version of the AWS SDK for Go V2.