Document HAP domain feature

Add HAP feature to schema and documentation.

docs/formatdomain.html.in

@@ -437,6 +437,7 @@
     <pae/>
     <acpi/>
     <apic/>
+    <hap/>
   </features>
   ...</pre>
 
@@ -456,6 +457,10 @@
       <dd>ACPI is useful for power management, for example, with
         KVM guests it is required for graceful shutdown to work.
       </dd>
+      <dt><code>hap</code></dt>
+      <dd>Enable use of Hardware Assisted Paging if available in
+        the hardware.
+      </dd>
     </dl>
 
     <h3><a name="elementsTime">Time keeping</a></h3>

docs/schemas/domain.rng

@@ -1748,7 +1748,7 @@
     </element>
   </define>
   <!--
-      A set of optional features: PAE, APIC and ACPI support
+      A set of optional features: PAE, APIC, ACPI, and HAP support
     -->
   <define name="features">
     <optional>
@@ -1769,6 +1769,11 @@
               <empty/>
             </element>
           </optional>
+          <optional>
+            <element name="hap">
+              <empty/>
+            </element>
+          </optional>
         </interleave>
       </element>
     </optional>