Update changelog for v0.4.0

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
-This is the changelog for NeoFS Proto
+This is the changelog for NeoFS API
+
+## [0.4.0] - 2020-02-18
+
+### Added 
+- Meta header for all gRPC responses. It contains epoch stamp and version number.
+### Changed
+- Endianness in accounting cheque. Now it uses little endian for cheaper
+decoding in neofs smart-contract.
 
 ## [0.3.2] - 2020-02-10
 
@@ -189,3 +197,4 @@ Initial public release
 [0.3.0]: https://github.com/nspcc-dev/neofs-api/compare/v0.2.14...v0.3.0
 [0.3.1]: https://github.com/nspcc-dev/neofs-api/compare/v0.3.0...v0.3.1
 [0.3.2]: https://github.com/nspcc-dev/neofs-api/compare/v0.3.1...v0.3.2
+[0.4.0]: https://github.com/nspcc-dev/neofs-api/compare/v0.3.2...v0.4.0