update CHANGELOG

Author: Phil Varner

CHANGELOG.md

@@ -15,6 +15,7 @@ For changes in 0.9.0 and prior, see the [STAC Spec Changelog](https://github.com
 ### Changed
 - Context Extension OpenAPI spec was updated to remove the no longer used `next` attribute
 - Added root endpoint Link `search` must have `type` of `application/geo+json`
+- Corrected the description of endpoint `/collections` to say it returns an object per OAFeat, instead of an array of Collection
 
 ### Fixed