README: Recommend check mode

README.md

@@ -22,10 +22,11 @@ Create `inventory.yml`. **Don't commit this file**, it contains site-specific co
 
 Deploy
 ------
-
+To deploy e.g. the jenkins master user:
 ```
-$ ansible-playbook -i ./inventory.yml ./install_jenkins.yml
+$ ansible-playbook -i ./inventory.yml ./install_jenkins.yml -s --check -l jenkinsmaster
 ```
+If everything looks o.k. rerun without *--check*.
 
 ### From within Jenkins
 -----------------------