Add some missing Changelog bits

CHANGELOG.md

@@ -14,7 +14,11 @@ Canonical reference for changes, improvements, and bugfixes for Boundary.
   [PR](https://github.com/hashicorp/boundary/pull/1220))
 * sessions: Add some missing API-level checks when session cancellation was
   requested. It's much easier than interpreting the domain-level check failures.
-  [PR](https://github.com/hashicorp/boundary/pull/1223))
+  ([PR](https://github.com/hashicorp/boundary/pull/1223))
+* authenticate: When authenticating with OIDC and `json` format output, the
+  command will no longer print out a notice that it's opening your web browser
+  ([Issue](https://github.com/hashicorp/boundary/issues/1193),
+  [PR](https://github.com/hashicorp/boundary/pull/1213))
 
 ## 0.2.1 (2021/05/05)