Merge branch 'timwiel-master-patch-12479' into 'master'

Update releases doc to reflect upcoming_release attribute

See merge request gitlab-org/gitlab!71017

doc/api/releases/index.md

@@ -729,3 +729,5 @@ Example response:
 
 A release with a `released_at` attribute set to a future date is labeled
 as an **Upcoming Release** [in the UI](../../user/project/releases/index.md#upcoming-releases).
+
+Additionally, if a [release is requested from the API](#list-releases), for each release with a `release_at` attribute set to a future date, an additional attribute `upcoming_release` (set to true) will be returned as part of the response.