libvirt: add documentation about SSH keypair requirements

README_libvirt.md

@@ -23,6 +23,7 @@ Install dependencies
 9.	Check that your `$HOME` is accessible to the qemu user²
 10.	Configure dns resolution on the host³
 11.	Install libselinux-python
+12.	Ensure you have an SSH private and public keypair at `~/.ssh/id_rsa` and `~/.ssh/id_rsa.pub`⁴
 
 #### ¹ Depending on your distribution, libvirt access may be denied by default or may require a password at each access.
 
@@ -103,6 +104,11 @@ sudo vi /etc/NetworkManager/dnsmasq.d/libvirt_dnsmasq.conf
 server=/example.com/192.168.55.1
 ```
 
+#### ⁴ Private and public keypair in ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub
+
+This playbook uses SSH keys to communicate with the libvirt-driven virtual machines.  At this time the names of those keys are fixed and cannot be changed.
+
+
 Test The Setup
 --------------