tools: Showing ExpirationPeriod if it is present in FaceStatus

Change-Id: I8e5b1350179830a1d12866c02c16393068e06369
Refs: #1686
diff --git a/docs/_static/nfd-status.xsd b/docs/_static/nfd-status.xsd
index 8f9f7cf..829ba7c 100644
--- a/docs/_static/nfd-status.xsd
+++ b/docs/_static/nfd-status.xsd
@@ -57,6 +57,7 @@
     <xs:element type="xs:nonNegativeInteger" name="faceId"/>
     <xs:element type="xs:anyURI" name="remoteUri"/>
     <xs:element type="xs:anyURI" name="localUri"/>
+    <xs:element type="xs:duration" name="expirationPeriod" maxOccurs="1" minOccurs="0"/>
     <xs:element type="nfd:bidirectionalPacketCountersType" name="packetCounters"/>
     <xs:element type="nfd:faceFlagsType" name="flags" maxOccurs="1" minOccurs="0"/>
   </xs:sequence>