Adding an example policy to libvirt documentation is not really a new feature.

The example was added upstream by v1.2.19-19-g29b5167:

commit 29b5167417483ef80f6c3fce12811b59a1e2bd55
Author: Jiri Denemark <jdenemar>
Date:   Tue Aug 4 14:05:52 2015 +0200

    examples: Add example polkit ACL rules
    
    Creating ACL rules is not exactly easy and existing examples are pretty
    simple. This patch adds a somewhat complex example which defines several
    roles. Admins can do everything, operators can do basic operations
    on any domain and several groups of users who act as operators but only
    on a limited set of domains.
    
    Signed-off-by: Jiri Denemark <jdenemar>

Verify this bug on libvirt-1.2.17-8.el7, verify steps as following
1.Create 4 users
#useradd user1
#useradd user2
#useradd user3
#useradd useradmin

2.Prepare 4 guests
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 -     rhel7.0                        shut off
 -     rhel7.2                        shut off
 -     vm1                            shut off
 -     vm2                            shut off


3.Enable the acl in the host
#cat /etc/libvirt/libvirtd.conf
access_drivers = [ "polkit" ]
auth_unix_rw = "none"
unix_sock_rw_perms = "0777"

#systemctl restart libvirtd


4.Copy example polkit ACL rules to /etc/polkit-1/rules.d/ directory
/usr/share/doc/libvirt-daemon-1.2.17/libvirt-acl.rules /etc/polkit-1/rules.d/

5.Modify the rules with following setting
<1.let user1 and user1's group only operate domain rhel7*
<2.let user2 and user2's group only operate domain vm*
<3.let user3 and user3's group could operate both domain rhel7* and domain vm*
<4.let useradmin have could operate all domains with all permissons 

#cat /etc/polkit-1/rules.d/libvirt-acl.rules
--
/* Basic operations and monitoring on a limited set of domains. */
var userA = new Role("userA");
userA.domains = /^rhel7/;
userA.users = ["user1"];
userA.groups = ["user1"];

var userB = new Role("userB");
userB.domains = /^vm/;
userB.users = ["user2"];
userB.groups = ["user2"];

--
/* Same as users but on any domain. */
var operator = new Role("operator");
operator.domains = /.*/;
operator.users = ["user3"];
operator.groups = ["user3"];

--
/* Full access. */
var admin = new Role("admin");
admin.users = ["useradmin"];
admin.groups = ["useradmin"];

6.login guest with user1, then connect the hyperv with system mode,
user1 can do all operations which defined in "restrictedActions"
in /etc/polkit-1/rules.d/libvirt-acl.rules by default, but only on
rhel7* guests

 virsh # list --all
 Id    Name                           State
----------------------------------------------------
 10    rhel7.0                        running
 11    rhel7.2                        running

7.login guest with user2, then connect the hyperv with system mode,
user1 can do all operations which defined in "restrictedActions"
in /etc/polkit-1/rules.d/libvirt-acl.rules by default, but only on
vm* guests

virsh # list --all
 Id    Name                           State
----------------------------------------------------
 12    vm1                            running
 13    vm2                            running

8.login guest with user3, then connect the hyperv with system mode,
user3 can do all operations which defined in "restrictedActions"
in /etc/polkit-1/rules.d/libvirt-acl.rules by default on all guests,
but couldn't do the ations outside  "restrictedActions"
virsh # list --all
 Id    Name                           State
----------------------------------------------------
 16    rhel7.0                        running
 17    rhel7.2                        running
 18    vm1                            running
 19    vm2                            running

virsh # net-destroy default
error: Failed to destroy network default
error: access denied

9.login guest with useradmin, then connect the hyperv with system mode,
useradmin can do all operations on all guests,

10.Add user1 to user2's group, then re-test step 7, user1 can do actions 
on domain vm*
virsh # list --all
 Id    Name                           State
----------------------------------------------------
 20    vm1                            running
 21    vm2                            running
 22    rhel7.2                        running
 23    rhel7.0                        running

11.Add user1 to useradmin's group, then re-test step7, user1 can operate
all operations on all domains

According to the upper steps, mark this bug verifed

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2202.html