config default: add comment

config/default.go

@@ -24,9 +24,24 @@ max_msg_recv_size = %[9]d
 conn_timeout = %[10]d
 pool_capacity = %[11]d
 
-[views]
-
+# views.channels is the view displaying channel list.
 [views.channels]
+# It is possible to add, remove and order columns of
+# the array. The default value is:
+# columns = [
+# "STATUS",
+# "ALIAS",
+# "GAUGE",
+# "LOCAL",
+# "CAP",
+# "HTLC",
+# "UNSETTLED",
+# "CFEE",
+# "LAST UPDATE",
+# "PRIVATE",
+# "ID",
+# ]
+
 columns = [
 	"STATUS",
 	"ALIAS",