chore(changelog): add v1.0.0 release notes

CHANGELOG.md

@@ -5,6 +5,13 @@ 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).
 
+## [1.0.0](https://github.com/IBM/carbon-icons-svelte/releases/tag/v1.0.0) - 2019-12-13
+
+- Breaking changes: remove `width`, `height` props, change `focusable` prop from string to boolean
+
+- Use `formatAttributes`, `toString` utilities from `@carbon/icon-helpers`
+  ([#4](https://github.com/IBM/carbon-icons-svelte/issues/4))
+
 ## [0.1.0](https://github.com/IBM/carbon-icons-svelte/releases/tag/v0.1.0) - 2019-12-13
 
-- Initial release (using `@carbon/[email protected]`, `@carbon/icons@10.4.0`)
+- Initial release (using `@carbon/[email protected]`, `@carbon/icon-helpers@10.4.0`)