Update placeholder assignment by CSV flag history

doc/user/project/import/_index.md

@@ -362,7 +362,7 @@ Before a user accepts the reassignment, you can [cancel the request](#cancel-rea
 
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-- [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/455901) in GitLab 17.10 [with a flag](../../../administration/feature_flags.md) named `importer_user_mapping_reassignment_csv`. Disabled by default.
+- [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/455901) in GitLab 17.10 [with a flag](../../../administration/feature_flags.md) named `importer_user_mapping_reassignment_csv`. [Enabled on GitLab.com](https://gitlab.com/gitlab-org/gitlab/-/issues/478022).
 
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