Add documentation for IPv6 and network routes

Author: damfle

README.md

@@ -44,6 +44,18 @@ should be a dict containing the following items:
    name (optional).
 - `dhcp_start` First IP of the DHCP range in `route` or `nat` mode (optional).
 - `dhcp_end` Last IP of the DHCP range in `route` or `nat` mode (optional).
+- `routes` Optional list of additionals routes defined as following:
+  - `address` Address of the route, required.
+  - `prefix` Prefix of the route, required.
+  - `gateway` Gateway of the route, required.
+  - `metric` Metric of the route (optional).
+- `ip6` IPv6 address of the virtual bridge (optional).
+- `ip6_prefix` IPv6 prefix of the virtual bridge (optional).
+- `routesv6` Optional list of additionals IPv6 routes defined as following:
+  - `address` IPv6 address of the route, required.
+  - `prefix` IPv6 previx of the route, required.
+  - `gateway` gateway of the route, required.
+  - `metric` metric of the route (optional).
 
 `libvirt_host_require_vt` is whether to require that Intel Virtualisation
 Technology (VT) is enabled in order to run this role. While this provides