Document that the default log priority is error, not critical

(cherry picked from commit a7a98d8bbb8976a7c55a734f1ac420c5d43763a8)

include/SDL_log.h

@@ -59,7 +59,7 @@ extern "C" {
  *  By default the application category is enabled at the INFO level,
  *  the assert category is enabled at the WARN level, test is enabled
  *  at the VERBOSE level and all other categories are enabled at the
- *  CRITICAL level.
+ *  ERROR level.
  */
 typedef enum
 {