Prepare for v3.9.0 release

CHANGELOG.md

@@ -2,12 +2,16 @@ CHANGELOG
 =========
 
 ## HEAD (Unreleased)
-* Upgrade to Pulumi v2.12.0
-* Upgrade to Pulumi v2.12.0 and pulumi-terraform-bridge v2.11.0
-* Improving the accuracy of previews leading to a more accurate understanding of what will actually change rather than assuming all output properties will change
+_(none)_
 
 ---
 
+## 3.9.0 (2020-10-23)
+* Upgrade to Pulumi v2.12.0 and pulumi-terraform-bridge v2.11.0
+* Improving the accuracy of previews leading to a more accurate understanding of what will actually change rather than assuming all output properties will change.  
+  ** PLEASE NOTE:**  
+  This new preview functionality can be disabled by setting `PULUMI_DISABLE_PROVIDER_PREVIEW` to `1` or `false`.
+
 ## 3.8.0 (2020-10-16)
 * Upgrade to v3.11.0 of the AWS Terraform Provider