Bump ansible_version_min to 2.4

Change-Id: I6875cde5c3cc7775c39011816c513e73df3396db

doc/source/user/quickstart.rst

@@ -74,7 +74,7 @@ Install dependencies
    .. note::
 
       Some implemented distro versions of Ansible are too old to use distro
-      packaging. Currently, CentOS and RHEL package Ansible >=2.2 which is suitable
+      packaging. Currently, CentOS and RHEL package Ansible >=2.4 which is suitable
       for use with Kolla. Note that you will need to enable access to the EPEL
       repository to install via :command:`yum` to do so, take a look at `Fedora's EPEL docs
       <https://fedoraproject.org/wiki/EPEL>`__ and `FAQ