Fix typo in comment.
Author: Haiying Tang
Discussion:
/* defaults for costsize.c's Cost parameters */
/* NB: cost-estimation code should use the variables, not these constants! */
-/* If you change these, update backend/utils/misc/postgresql.sample.conf */
+/* If you change these, update backend/utils/misc/postgresql.conf.sample */
#define DEFAULT_SEQ_PAGE_COST 1.0
#define DEFAULT_RANDOM_PAGE_COST 4.0
#define DEFAULT_CPU_TUPLE_COST 0.01
