luna: Adjust cstyle_format's description

libluna/include/luna/Format.h

@@ -5,7 +5,8 @@
 
 typedef Result<void> (*callback_t)(char, void*);
 
-// Used to format anything that can fail (writing to C FILEs, etc...)
+// Format output according to a format string and a list of variadic arguments. callback is called with arg for every
+// character in the resulting string.
 Result<usize> cstyle_format(const char* format, callback_t callback, void* arg, va_list ap);
 
 // Convenience function which outputs into a fixed-size buffer (not unlike vsnprintf)