Update CHANGELOG.md

Author: Paddy

CHANGELOG.md

@@ -4,10 +4,12 @@ ENHANCEMENTS
 
 * Convenience methods were added to the `diag` package to simplify common error cases [GH-449]
 * Removed the `helper/mutexkv`, `helper/pathorcontents`, `httpclient`, and `helper/hashcode` packages. These packages can be easily replicated in plugin code if necessary or the v1 versions can be used side-by-side [GH-438]
+* The test driver was reworked to allow for test coverage, race detection, and debugger support. [GH-471]
 
 BREAKING CHANGES
 
 * Removed `schema.PanicOnErr/TF_SCHEMA_PANIC_ON_ERR` environment variable. `d.Set()` errors are now logged in production and panic during acceptance tests (`TF_ACC=1`). [GH-462]
+* Running provider tests now requires Terraform 0.12.26 or higher. [GH-471]
 
 # 2.0.0-rc.1 (May 05, 2020)