Show how the config/storage directory can be mounted on the host under docker.

pkg/docker/README

@@ -64,9 +64,10 @@ docker run -p 80:80 \
            -e "PGADMIN_DEFAULT_PASSWORD=SuperSecret" \
            -d pgadmin4
 
-Run a TLS secured container:
+Run a TLS secured container using a shared config/storage directory in /private/var/lib/pgadmin on the host:
 
 docker run -p 443:443 \
+           -v "/private/var/lib/pgadmin:/var/lib/pgadmin" \
            -v "/path/to/certificate.cert:/certs/server.cert" \
            -v "/path/to/certificate.key:/certs/server.key" \
            -e "PGADMIN_DEFAULT_EMAIL=user@domain.com" \