Changelog updates [skip ci]

Author: cinemast

CHANGELOG.md

@@ -5,6 +5,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [UNRELEASED]
+### Changed
+- Updated cpp-httplib to v0.8.4
+
+### Added
+- Enum for specified JSON-RPC error codes (#17)
+
+### Fixed
+- RPC methods expecting floats\doubles could be called with an integral type which would throw an exception (#18)
+
 ## [0.2.1] - 2020-10-21
 ### Changed
 - Updated Catch to version 2.13.2