Note on how to install a specific Ansible version

README.md

@@ -9,7 +9,7 @@ These Ansible roles allow you to install, from a deployment host, iRODS [4.2.0 -
 
 ```bash
 yum install python2-pip # as root
-pip install ansible --user # first installation
+pip install ansible==2.9.0 --user # first installation
 pip install -U ansible --user # update
 ```