Link DRF Condition (cache headers) third party package. (#6557)

docs/community/third-party-packages.md

@@ -263,6 +263,7 @@ To submit new content, [open an issue][drf-create-issue] or [create a pull reque
 * [django-rest-messaging][django-rest-messaging], [django-rest-messaging-centrifugo][django-rest-messaging-centrifugo] and [django-rest-messaging-js][django-rest-messaging-js] - A real-time pluggable messaging service using DRM.
 * [djangorest-alchemy][djangorest-alchemy] - SQLAlchemy support for REST framework.
 * [djangorestframework-datatables][djangorestframework-datatables] - Seamless integration between Django REST framework and [Datatables](https://datatables.net).
+* [django-rest-framework-condition][django-rest-framework-condition] - Decorators for managing HTTP cache headers for Django REST framework (ETag and Last-modified).
 
 [cite]: http://www.software-ecosystems.com/Software_Ecosystems/Ecosystems.html
 [cookiecutter]: https://github.com/jpadilla/cookiecutter-django-rest-framework
@@ -336,3 +337,4 @@ To submit new content, [open an issue][drf-create-issue] or [create a pull reque
 [drfpasswordless]: https://github.com/aaronn/django-rest-framework-passwordless
 [djangorest-alchemy]: https://github.com/dealertrack/djangorest-alchemy
 [djangorestframework-datatables]: https://github.com/izimobil/django-rest-framework-datatables
+[django-rest-framework-condition]: https://github.com/jozo/django-rest-framework-condition