Document lazy failovers in Praefect

doc/administration/gitaly/index.md

@@ -186,7 +186,8 @@ Gitaly Cluster supports:
 - [Strong consistency](praefect.md#strong-consistency) of the secondary replicas.
 - [Automatic failover](praefect.md#automatic-failover-and-primary-election-strategies) from the primary to the secondary.
 - Reporting of possible data loss if replication queue is non-empty.
-- Marking repositories as [read-only](praefect.md#read-only-mode) if data loss is detected to prevent data inconsistencies.
+- From GitLab 13.0 to GitLab 14.0, marking repositories as [read-only](praefect.md#read-only-mode)
+  if data loss is detected to prevent data inconsistencies.
 
 Follow the [Gitaly Cluster epic](https://gitlab.com/groups/gitlab-org/-/epics/1489)
 for improvements including