remove coreapi doc & redirect broken links to github snapshot

Author: tfranzel

docs/community/3.4-announcement.md

@@ -187,7 +187,7 @@ The full set of itemized release notes [are available here][release-notes].
 [api-blueprint]: https://apiblueprint.org/
 [tut-7]: ../tutorial/7-schemas-and-client-libraries/
 [schema-generation]: ../api-guide/schemas/
-[api-clients]: ../topics/api-clients.md
+[api-clients]: https://github.com/encode/django-rest-framework/blob/3.14.0/docs/topics/api-clients.md
 [milestone]: https://github.com/encode/django-rest-framework/milestone/35
 [release-notes]: release-notes#34
 [metadata]: ../api-guide/metadata/#custom-metadata-classes

docs/community/3.6-announcement.md

@@ -195,5 +195,5 @@ on realtime support, for the 3.7 release.
 [sponsors]: https://fund.django-rest-framework.org/topics/funding/#our-sponsors
 [funding]: funding.md
 [api-docs]: ../topics/documenting-your-api.md
-[js-docs]: ../topics/api-clients.md#javascript-client-library
-[py-docs]: ../topics/api-clients.md#python-client-library
+[js-docs]: https://github.com/encode/django-rest-framework/blob/3.14.0/docs/topics/api-clients.md#javascript-client-library
+[py-docs]: https://github.com/encode/django-rest-framework/blob/3.14.0/docs/topics/api-clients.md#python-client-library