tools: Extend nfdc to allow creation of permanent faces

Change-Id: If108fc3c7ae2ba1adab50269db3a23b426553b56
Refs: #2993
diff --git a/docs/manpages/nfdc.rst b/docs/manpages/nfdc.rst
index af6764b..d06b519 100644
--- a/docs/manpages/nfdc.rst
+++ b/docs/manpages/nfdc.rst
@@ -76,7 +76,15 @@
   ``create``
     Create a UDP unicast or TCP Face
 
-    ``create <faceUri>``
+    ``create [-P] <faceUri>``
+
+      ``-P``
+        create permanent (instead of persistent) face:
+
+        .. note::
+          Persistent (default) faces remain open until they are explicitly destroyed or
+          there is a transport failure.  Permanent faces remain open until they are
+          explicitly destroyed; any transport failures will be recovered internally.
 
       ``faceUri``
         UDP unicast or TCP Face URI::