Merge pull request #169 from avadev/21.2.1

Update README.md

Author: svc-developer

README.md

@@ -98,6 +98,12 @@ return client.resolveAddress(address)
   });
 
 ```
+## Release Notes
+
+In the JS-SDK 21.2.1 release, the SDK can now return big integers from API responses.
+Big integers in JavaScript are displayed in responses by appending an 'n' to the end of an integer literal. For example, 618368842515476464 -> 618368842515476464n.
+Numbers are presented as before. For example, 8456123 -> 8456123.
+For more information, refer to the following Mozilla documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt
 
 ## SDK Development