chore(printf): update comments

printf.h

@@ -83,8 +83,8 @@ int vsnprintf(char* buffer, size_t count, const char* format, va_list va);
 /**
  * printf with output function
  * You may use this as dynamic alternative to printf() with its fixed _putchar() output
- * \param out An output function which takes one character
- * \param user A pointer to user data passed to output function
+ * \param out An output function which takes one character and an argument pointer
+ * \param arg An argument pointer for user data passed to output function
  * \param format A string that specifies the format of the output
  * \return The number of characters that are sent to the output function, not counting the terminating null character
  */