Add more detail for Praefect auto reconciliation

doc/administration/gitaly/praefect.md

@@ -1196,9 +1196,16 @@ CAUTION: **Caution:**
 
 ## Data recovery
 
-If a Gitaly node fails replication jobs for any reason, it ends up hosting outdated versions of
-the affected repositories. Praefect provides tools for automatically or manually reconciling
-the outdated repositories in order to bring them fully up to date again.
+If a Gitaly node fails replication jobs for any reason, it ends up hosting outdated versions of the
+affected repositories. Praefect provides tools for:
+
+- [Automatic](#automatic-reconciliation) reconciliation, for GitLab 13.4 and later.
+- [Manual](#manual-reconciliation) reconciliation, for:
+  - GitLab 13.3 and earlier.
+  - Repositories upgraded to GitLab 13.4 and later without entries in the `repositories` table.
+    A migration tool [is planned](https://gitlab.com/gitlab-org/gitaly/-/issues/3033).
+
+These tools reconcile the outdated repositories to bring them fully up to date again.
 
 ### Automatic reconciliation