Update CHANGELOG for v1.0.0

***NO_CI***

Author: nfbot

CHANGELOG.md

@@ -2,7 +2,19 @@
 
 ## [**Changes available only in 'Preview' NuGet packages:**](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/tree/HEAD)
 
-[Full Changelog](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/compare/v1.0.0-preview.18...HEAD)
+[Full Changelog](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/compare/v1.0.0-preview.20...HEAD)
+
+**Implemented enhancements:**
+
+- Improve readme [\#1](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/pull/1)
+
+**Documentation and other chores:**
+
+- Update 1 nuget dependencies [\#3](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/pull/3)
+
+## [v1.0.0-preview.20](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/tree/v1.0.0-preview.20) (2021-10-18)
+
+[Full Changelog](https://github.com/nanoframework/nanoFramework.Aws.IoTCore.Devices/compare/v1.0.0-preview.18...v1.0.0-preview.20)
 
 **Documentation and other chores:**