Add CHANGELOG entry

Signed-off-by: Filip Petkovski <[email protected]>

Author: fpetkovski

CHANGELOG.md

@@ -57,6 +57,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#150](https://github.com/thanos-io/objstore/pull/150) Add support for roundtripper wrapper.
 - [#63](https://github.com/thanos-io/objstore/pull/63) Implement a `IterWithAttributes` method on the bucket client.
 - [#155](https://github.com/thanos-io/objstore/pull/155) Add a `Provider` method on `objstore.Client`.
+- [#163](https://github.com/thanos-io/objstore/pull/145) Add a `NewBucketFromConfig` constructor method for creating a client from an existing `BucketConfig` object.
 
 
 ### Changed