added serialzed dictionary

Packages/SerializedDictionary-main/Samples~/Usage/SerializedDictionarySample.cs

@@ -0,0 +1,20 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace AYellowpaper.SerializedCollections
+{
+    public class SerializedDictionarySample : MonoBehaviour
+    {
+        [SerializedDictionary("Element Type", "Description")]
+        public SerializedDictionary<ElementType, string> ElementDescriptions;
+        
+        public enum ElementType
+        {
+            Fire,
+            Air,
+            Earth,
+            Water
+        }
+    }
+}