ansible-freeipa roles do not work with Ansible 2.8 anymore, so the
minimum supported version is changed to 2.15, the oldest supported
Ansible version as of today.
Currently, the minimum supported Ansible version is 2.13, and
ansible-freeipa roles does not work with any version less than 2.9,
altough ansible-freeipa documentation states that the minimum version to
use is 2.8.
This patch fixes documentation and roles metadata to require that the
minimum Ansible version used is 2.13.
The dependency is either working with galaxy or with local role collection
but not with both because the role name is for the first t_woerner.ipaclient
but for the second it needs to be ipaclient only.
