updated message in api changelog

Author: hzoppetti

src/content/changelog/4-78-3-2020-10-20-2020.md

@@ -7,6 +7,9 @@ changelog:
 ---
 
 ### Changed
-- The [API v4 spec](http://www.linode.com/docs/api) has been moved to reside in the new [Linode Docs site](http://www.linode.com/docs). The links within the spec file have been updated to reflect this new location.
+- Linode's [API v4 documentation](http://www.linode.com/docs/api) has been moved to reside in the new [Linode Docs site](http://www.linode.com/docs).
+
+  - Our OpenAPI specification can now be downloaded at https://www.linode.com/docs/api/openapi.yaml.
+  - Any links within the spec file have been updated to reflect this new location.
 
 - All links within [API changelog](https://developers.linode.com/changelog/api/) entries have been updated to reflect the new location of the [API v4 spec](http://www.linode.com/docs/api) file.