Fix typo in comments.

Author: Hou Zhijie
Discussion: https://postgr.es/m/OS0PR01MB5716E6A6535FDFDC5A1B004194CE9@OS0PR01MB5716.jpnprd01.prod.outlook.com

Author: MasaoFujii

src/backend/parser/gram.y

@@ -2284,7 +2284,7 @@ alter_table_cmd:
 					n->def = (Node *) $5;
 					$$ = (Node *)n;
 				}
-			/* ALTER TABLE <name> ALTER [COLUMN] <colname> RESET ( column_parameter = value [, ... ] ) */
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> RESET ( column_parameter [, ... ] ) */
 			| ALTER opt_column ColId RESET reloptions
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);

src/backend/utils/adt/xid8funcs.c

@@ -369,7 +369,7 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 }
 
 /*
- * Same as pg_current_xact_if_assigned() but doesn't assign a new xid if there
+ * Same as pg_current_xact_id() but doesn't assign a new xid if there
  * isn't one yet.
  */
 Datum