[LEAK INFORMED] Documented the unk19 item field

include/item.h

@@ -14,7 +14,7 @@ struct Item
     u8 holdEffectParam;
     const u8 *description;
     u8 importance;
-    u8 unk19;
+    u8 registrability;
     u8 pocket;
     u8 type;
     ItemUseFunc fieldUseFunc;
@@ -68,7 +68,7 @@ u8 ItemId_GetHoldEffect(u16 itemId);
 u8 ItemId_GetHoldEffectParam(u16 itemId);
 const u8 *ItemId_GetDescription(u16 itemId);
 u8 ItemId_GetImportance(u16 itemId);
-u8 ItemId_GetUnknownValue(u16 itemId);
+u8 ItemId_GetRegistrability(u16 itemId);
 u8 ItemId_GetPocket(u16 itemId);
 u8 ItemId_GetType(u16 itemId);
 ItemUseFunc ItemId_GetFieldFunc(u16 itemId);