Add recursive chown in docs

Author: reqlez

README.md

@@ -20,7 +20,7 @@ The current oracle core is built to run the protocol specified in the [EIP-0023
 
 AMD64 and ARM64 images are available from [Docker Hub Repo](https://hub.docker.com/r/ergoplatform/oracle-core)
 
-The container runs under oracle-core user ( 9010 uid ), if using bind mount for container's /data folder ( where config files and other data lives ), set the container's uid for the host's folder ownership ( ex: chown 9010:9010 oracle_data ).
+The container runs under oracle-core user ( 9010 uid ), if using bind mount for container's /data folder ( where config files and other data lives ), set the container's uid for the host's folder ownership ( ex: chown -R 9010:9010 oracle_data ).
 
 An example docker run command: