mysql/mariadb/percona: note a way to restore data from dump file.

mariadb/content.md

@@ -157,3 +157,11 @@ Most of the normal tools will work, although their usage might be a little convo
 ```console
 $ docker exec some-%%REPO%% sh -c 'exec mysqldump --all-databases -uroot -p"$MYSQL_ROOT_PASSWORD"' > /some/path/on/your/host/all-databases.sql
 ```
+
+## Restoring data from dump files
+
+For restoring data. You can use `docker exec` command with `-i` flag, similar to the following:
+
+```console
+$ docker exec -i some-%%REPO%% sh -c 'exec mysql -uroot -p"$MYSQL_ROOT_PASSWORD"' < /some/path/on/your/host/all-databases.sql
+```

mysql/content.md

@@ -174,3 +174,11 @@ Most of the normal tools will work, although their usage might be a little convo
 ```console
 $ docker exec some-%%REPO%% sh -c 'exec mysqldump --all-databases -uroot -p"$MYSQL_ROOT_PASSWORD"' > /some/path/on/your/host/all-databases.sql
 ```
+
+## Restoring data from dump files
+
+For restoring data. You can use `docker exec` command with `-i` flag, similar to the following:
+
+```console
+$ docker exec -i some-%%REPO%% sh -c 'exec mysql -uroot -p"$MYSQL_ROOT_PASSWORD"' < /some/path/on/your/host/all-databases.sql
+```

percona/content.md

@@ -179,3 +179,11 @@ Most of the normal tools will work, although their usage might be a little convo
 ```console
 $ docker exec some-%%REPO%% sh -c 'exec mysqldump --all-databases -uroot -p"$MYSQL_ROOT_PASSWORD"' > /some/path/on/your/host/all-databases.sql
 ```
+
+## Restoring data from dump files
+
+For restoring data. You can use `docker exec` command with `-i` flag, similar to the following:
+
+```console
+$ docker exec -i some-%%REPO%% sh -c 'exec mysql -uroot -p"$MYSQL_ROOT_PASSWORD"' < /some/path/on/your/host/all-databases.sql
+```