Update changelog

Author: sliverc

CHANGELOG.md

@@ -18,14 +18,15 @@ any parts of the framework not mentioned in the documentation should generally b
 
 * Allow to define `select_related` per include using [select_for_includes](https://django-rest-framework-json-api.readthedocs.io/en/stable/usage.html#performance-improvements)
 * Reduce number of queries to calculate includes by using `select_related` when possible
+* Use REST framework serializer functionality to extract includes. This adds support like using
+  dotted notations in source attribute in `ResourceRelatedField`.
 
 ### Fixed
 
 * Avoid exception when trying to include skipped relationship
 * Don't swallow `filter[]` params when there are several
 * Fix DeprecationWarning regarding collections.abc import in Python 3.7
 * Allow OPTIONS request to be used on RelationshipView
-* Use DRF code when extracting relation instance. [PR](https://github.com/django-json-api/django-rest-framework-json-api/pull/632)
 
 ### Deprecated