Add comment for VirtualizedList props not supported by FlatList (#500)

Author: sgny

reason-react-native/src/components/FlatList.md

@@ -5,6 +5,10 @@ wip: true
 ---
 
 ```reason
+// VirtualizedList props data, getItem, getItemCount and getItemLayout
+// are not supported on FlatList
+// FlatList has its own data prop, specified as array(item)
+
 include VirtualizedListElement;
 
 type separatorComponentProps('item) = {

reason-react-native/src/components/FlatList.re

@@ -1,3 +1,7 @@
+// VirtualizedList props data, getItem, getItemCount and getItemLayout
+// are not supported on FlatList
+// FlatList has its own data prop, specified as array(item)
+
 include VirtualizedListElement;
 
 type separatorComponentProps('item) = {