uses DB_NAME for sql backup dump

backup.sh

@@ -29,4 +29,4 @@ docker exec "${PREFIX}-db" \
   /usr/bin/mysqldump \
   -u root \
   --password="${DB_ROOT_PASSWORD}" \
-  "${DB_NAME}" > "${backup_path}/db/dump.sql"
+  "${DB_NAME}" > "${backup_path}/db/${DB_NAME}.sql"