Rename guc, which connected with setting minimum number of neighbours for predicting

and add more understandable explanations of guc.

Author: Alena Rybakina

aqo.c

@@ -294,8 +294,8 @@ _PG_init(void)
 							NULL
 	);
 
-	DefineCustomIntVariable("aqo.k_neighbors_threshold",
-							"Set the threshold of number of neighbors for predicting.",
+	DefineCustomIntVariable("aqo.min_neighbors_for_predicting",
+							"Set how many neighbors the cardinality prediction will be calculated",
 							NULL,
 							&aqo_k,
 							3,
@@ -307,7 +307,7 @@ _PG_init(void)
 							NULL);
 
 	DefineCustomBoolVariable("aqo.predict_with_few_neighbors",
-							"Make prediction with less neighbors than we should have.",
+							"Establish the ability to make predictions with fewer neighbors than were found.",
 							 NULL,
 							 &aqo_predict_with_few_neighbors,
 							 true,

expected/look_a_like.out

@@ -3,7 +3,7 @@ SET aqo.join_threshold = 0;
 SET aqo.mode = 'learn';
 SET aqo.show_details = 'on';
 set aqo.show_hash = 'off';
-SET aqo.k_neighbors_threshold = 1;
+SET aqo.min_neighbors_for_predicting = 1;
 SET enable_nestloop = 'off';
 SET enable_mergejoin = 'off';
 SET enable_material = 'off';

sql/look_a_like.sql

@@ -3,7 +3,7 @@ SET aqo.join_threshold = 0;
 SET aqo.mode = 'learn';
 SET aqo.show_details = 'on';
 set aqo.show_hash = 'off';
-SET aqo.k_neighbors_threshold = 1;
+SET aqo.min_neighbors_for_predicting = 1;
 SET enable_nestloop = 'off';
 SET enable_mergejoin = 'off';
 SET enable_material = 'off';