Document item use functions in pokemon.c

include/constants/pokemon.h

@@ -213,4 +213,9 @@
 #define UNOWN_FORM_COUNT 28
 #define BOX_NAME_LENGTH 8
 
+#define EVOTRIGGER_LEVEL_UP    0
+#define EVOTRIGGER_TRADE       1
+#define EVOTRIGGER_STONE       2
+#define EVOTRIGGER_STONE_2     3
+
 #endif // GUARD_CONSTANTS_POKEMON_H