mgmt: Add tables.network_region section in config file to populate NetworkRegionTable

refs: #3159

Change-Id: If049eea2baf64a22abc9437d3ec117dd0d27bbab
diff --git a/nfd.conf.sample.in b/nfd.conf.sample.in
index 65d9def..24407c7 100644
--- a/nfd.conf.sample.in
+++ b/nfd.conf.sample.in
@@ -58,6 +58,16 @@
     /localhost/nfd  /localhost/nfd/strategy/best-route
     /ndn/broadcast  /localhost/nfd/strategy/multicast
   }
+
+  ; Declare network region names
+  ; These are used for mobility support.  An Interest carrying a Link object is
+  ; assumed to have reached the producer region if any delegation name in the
+  ; Link object is a prefix of any region name.
+  network_region
+  {
+    ; /example/region1
+    ; /example/region2
+  }
 }
 
 ; The face_system section defines what faces and channels are created.