Update i_u_m_update.md

docs/i_u_m_update.md

@@ -62,6 +62,7 @@ See the topic above, instead of diff, run...
 docker-compose down
 # Replace commit ID 22cd00b5e28893ef9ddef3c2b5436453cc5223ab by your ID
 git checkout 22cd00b5e28893ef9ddef3c2b5436453cc5223ab
+docker-compose pull
 docker-compose up -d
 ```