Fix two typos, by Fujii Masao.

src/backend/access/transam/xlog.c

@@ -3087,10 +3087,10 @@ not_available:
  *
  * 'command' is the shell command to be executed, 'commandName' is a
  * human-readable name describing the command emitted in the logs. If
- * 'failonSignal' is true and the command is killed by a signal, a FATAL
+ * 'failOnSignal' is true and the command is killed by a signal, a FATAL
  * error is thrown. Otherwise a WARNING is emitted.
  *
- * This is currently used for restore_end_command and archive_cleanup_command.
+ * This is currently used for recovery_end_command and archive_cleanup_command.
  */
 static void
 ExecuteRecoveryCommand(char *command, char *commandName, bool failOnSignal)