Update CHANGELOG for v1.0.5

***NO_CI***

Author: nfbot

CHANGELOG.md

@@ -2,7 +2,14 @@
 
 ## [**Changes available only in 'Preview' NuGet packages:**](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/tree/HEAD)
 
-[Full Changelog](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/compare/v1.0.5-preview-024...HEAD)
+[Full Changelog](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/compare/v1.0.5-preview-026...HEAD)
+
+**Documentation and other chores:**
+
+- Improve documentation comments [\#25](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/pull/25)
+
+## [v1.0.5-preview-026](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/tree/v1.0.5-preview-026) (2019-04-05)
+[Full Changelog](https://github.com/nanoframework/lib-nanoFramework.System.Net.Http/compare/v1.0.5-preview-024...v1.0.5-preview-026)
 
 **Implemented enhancements:**