Readne: update "Limitations" section

Author: gsmolk

README.md

@@ -49,6 +49,7 @@ Regardless of the chosen backup type, all backups taken with `pg_probackup` supp
 `pg_probackup` currently has the following limitations:
 * The server from which the backup was taken and the restored server must be compatible by the [block_size](https://postgrespro.com/docs/postgresql/current/runtime-config-preset#GUC-BLOCK-SIZE) and [wal_block_size](https://postgrespro.com/docs/postgresql/current/runtime-config-preset#GUC-WAL-BLOCK-SIZE) parameters and have the same major release number.
 * Remote backup via ssh on Windows currently is not supported.
+* When running remote operations via ssh, remote and local pg_probackup versions must be the same.
 
 ## Current release