Update CHANGELOG for v1.0.2-preview-012

Author: nfbot

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Change Log
 
+## [**Changes available only in 'Preview' NuGet packages:**](https://github.com/nanoframework/lib-nanoFramework.Networking.Sntp/tree/HEAD)
+
+[Full Changelog](https://github.com/nanoframework/lib-nanoFramework.Networking.Sntp/compare/v1.0.2-preview-005...HEAD)
+
+**Documentation and other chores:**
+
+- Bumps nanoFramework.CoreLibrary from 1.0.6-preview-001 to 1.0.6-preview-010 [\#20](https://github.com/nanoframework/lib-nanoFramework.Networking.Sntp/pull/20)
+
 ## [v1.0.2-preview-005](https://github.com/nanoframework/lib-nanoFramework.Networking.Sntp/tree/v1.0.2-preview-005) (2018-11-08)
 [Full Changelog](https://github.com/nanoframework/lib-nanoFramework.Networking.Sntp/compare/v1.0.2-preview-002...v1.0.2-preview-005)