Update the migration type

doc/update/index.md

@@ -298,7 +298,7 @@ and [Helm Chart deployments](https://docs.gitlab.com/charts/). They come with ap
 Ruby 2.7.4 is required. Refer to [the Ruby installation instructions](../install/installation.md#2-ruby)
 for how to proceed.
 
-- GitLab 14.3.0 contains background migrations to [address Primary Key overflow risk for tables with an integer PK](https://gitlab.com/groups/gitlab-org/-/epics/4785) for the tables listed below:
+- GitLab 14.3.0 contains post-deployment migrations to [address Primary Key overflow risk for tables with an integer PK](https://gitlab.com/groups/gitlab-org/-/epics/4785) for the tables listed below:
 
   - [`ci_builds.id`](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70245)
   - [`ci_builds.stage_id`](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/66688)