Repair error apparently introduced in the initial coding of GUC: the

default value for geqo_effort is supposed to be 40, not 1.  The actual
'genetic' component of the GEQO algorithm has been practically disabled
since 7.1 because of this mistake.  Improve documentation while at it.

src/backend/utils/misc/postgresql.conf.sample

@@ -123,10 +123,10 @@
 
 #geqo = true
 #geqo_threshold = 11
-#geqo_effort = 1
-#geqo_generations = 0
 #geqo_pool_size = 0		# default based on tables in statement,
 				# range 128-1024
+#geqo_generations = 0		# use default: effort * log2(pool_size)
+#geqo_effort = 40		# range 1-100
 #geqo_selection_bias = 2.0	# range 1.5-2.0
 
 # - Other Planner Options -