Update CHANGELOG.md (#22)

CHANGELOG.md

@@ -1,10 +1 @@
-## 0.2
-
-- Deprecate `channel` input, replaced by `sdk` input
-- The `sdk` input accepts either a channel _(which infers `latest` as the version)_, or a specific version string from any of the three release channels.
-  > See [Matrix Testing](./README.md#matrix-testing) for an example. 
-
-## Initial version (0.1)
-
-- Basic download and setup.
-- Support for Linux, macOS, and Windows.
+Please see the [version history](https://github.com/dart-lang/setup-dart/blob/main/README.md#version-history) in the README.md file.