Update PCI passthrough and SR-IOV glossary entries.

PCI Passthrough and, as a result, SR-IOV are available from OpenStack
Havana onwards. As such the relevant glossary entries have been updated
to indicate that these previously unsupported virtualization
technologies are now supported.

https://blueprints.launchpad.net/nova/+spec/pci-passthrough-base
https://blueprints.launchpad.net/nova/+spec/pci-passthrough-libvirt

Change-Id: I7468f62465ef5eaccefbb5dd188571965f987b3d

doc/glossary/glossary-terms.xml

@@ -3253,8 +3253,8 @@ daemon that provides
             <glossterm>PCI passthrough</glossterm>
             <glossdef>
                 <para>Allows guest VMs to have exclusive access to a
-                    PCI device, currently unsupported in
-                    OpenStack.</para>
+                    PCI device, currently supported in OpenStack Havana
+                    and later releases.</para>
             </glossdef>
         </glossentry>
         <glossentry>
@@ -4052,8 +4052,13 @@ daemon that provides
             <glossterm>Single-root I/O Virtualization
                 (SR-IOV)</glossterm>
             <glossdef>
-                <para>Alternative term for PCI pass-through. Currently
-                    unsupported in OpenStack.</para>
+                <para>A specification that when implemented by a physical PCIe
+                    device allows it to be presented as multiple separate
+                    PCIe devices. This allows multiple virtualized guests
+                    to share direct access to the physical device, offering
+                    improved performance over an equivalent virtual device.
+                    Currently supported in OpenStack Havana and later
+                    releases.</para>
             </glossdef>
         </glossentry>
         <glossentry>