Docs for MT convertation

docs/en/engines/table-engines/mergetree-family/replication.md

@@ -304,6 +304,12 @@ We use the term `MergeTree` to refer to all table engines in the `MergeTree fami
 
 If you had a `MergeTree` table that was manually replicated, you can convert it to a replicated table. You might need to do this if you have already collected a large amount of data in a `MergeTree` table and now you want to enable replication.
 
+`MergeTree` table can be automatically converted on server restart if `convert_to_replicated` flag is set at the table's flags directory (`/var/lib/clickhouse/data/db_name/table_name/flags/`). 
+This directory is not created by default, so you need to create it first. 
+Then simply create empty `convert_to_replicated` file and the table will be loaded as replicated on next server restart.
+
+There is also a manual way to do this without server restart.
+
 If the data differs on various replicas, first sync it, or delete this data on all the replicas except one.
 
 Rename the existing MergeTree table, then create a `ReplicatedMergeTree` table with the old name.