add changelog

Author: LimpidCrypto

CHANGELOG.md

@@ -10,9 +10,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Models
 - Integration Tests
 - Performance Benchmarks
+- Utility functions
 
 ## [[Unreleased]]
 
+- add missing NFT request models
+- add `parse_nftoken_id` and `get_nftoken_id` utility functions
+- complete existing result models and add NFT result models
+- add transaction `Metadata` models
+- fix serialization issue where null values were tried to be serialized
+- fix multisigning bug, because `signing_pub_key` is not set for multisigning but it is required, so it's just an empty string
+
 ## [[v0.4.0]]
 
 - add amm support