fix sections list in sample configuration file

samples/knot.full.conf

@@ -7,8 +7,8 @@
 # This is a comment.
 
 #
-# There are 5 main sections of this config file:
-#   system, zones, interfaces, control and log
+# There are 7 main sections of this config file:
+#   system, interfaces, remotes, groups, zones, control and log
 #
 
 # Section 'system' contains general options for the server