fix syntax error in example config

etc/example.conf

@@ -230,14 +230,14 @@ nodes = {
 							# If arrays are used, we will generate multiple test cases with all
 							# possible combinations
 			{
-				"rates": 55.0,		# The sending rate in Hz
-				"values": 5,		# The number of values which should be send in each sample
-				"limit": 100		# The number of samples which should be send during this test case
+				rates = 55.0,		# The sending rate in Hz
+				values = 5,		# The number of values which should be send in each sample
+				limit = 100		# The number of samples which should be send during this test case
 			},
 			{
-				"rates": [ 5, 10, 30 ],	# An array of rates in Hz
-				"values": [ 2, 10, 20 ],# An array of number of values
-				"duration": 5		# The duration of the test case in seconds (depending on the sending rate)
+				rates = [ 5, 10, 30 ],	# An array of rates in Hz
+				values = [ 2, 10, 20 ],# An array of number of values
+				duration = 5		# The duration of the test case in seconds (depending on the sending rate)
 			}
 		)
 	},