Update README with EnumBitSet64 and property drawer screenshot

Author: gilzoide

Extras~/CustomDrawer.png

@@ -1,7 +1,27 @@
 # EnumBitSet
 A memory efficient `ISet` for enums that store data using bit masks for C#.
 
-Currently, there is an implementation using `int` as data (`EnumBitSet32<T>`),
-supporting enums with up to 32 values.
+Current implementations:
+- `EnumBitSet32<T>`: uses `int` as data, supporting enums with up to 32 values.
+- `EnumBitSet64<T>`: uses `long` as data, supporting enums with up to 64 values.
 
-In Unity, there's a custom property drawer for selecting the containing enums.
+## Unity Property Drawer
+In Unity, there's a custom property drawer for selecting the containing enums:
+
+```cs
+using EnumBitSet;
+using UnityEngine;
+
+public class ScriptWithEnumSet : MonoBehaviour
+{
+    public enum TestEnum
+    {
+        Zero, One, Two, Three
+    }
+
+    public EnumBitSet32<TestEnum> aBitset;
+    public EnumBitSet64<TestEnum> anotherBitset;
+}
+```
+
+![](Extras~/CustomDrawer.png)