mgmt: remove listen option from unix channel configuration

refs: #2188

Change-Id: I11adf075b03eab3d22f8160e5d619e3ed445dd29
diff --git a/nfd.conf.sample.in b/nfd.conf.sample.in
index 210ecba..eb0de12 100644
--- a/nfd.conf.sample.in
+++ b/nfd.conf.sample.in
@@ -64,11 +64,12 @@
 ; The face_system section defines what faces and channels are created.
 face_system
 {
-  ; The unix section contains settings of UNIX stream faces and channels.
+  ; The unix section contains settings of Unix stream faces and channels.
+  ; Unix channel is always listening; delete unix section to disable
+  ; Unix stream faces and channels.
   unix
   {
-    listen yes ; set to 'no' to disable UNIX stream listener, default 'yes'
-    path /var/run/nfd.sock ; UNIX stream listener path
+    path /var/run/nfd.sock ; Unix stream listener path
   }
 
   ; The tcp section contains settings of TCP faces and channels.