Update changelog for Stacks ForceDelete

Author: hashimoon

CHANGELOG.md

@@ -1,5 +1,9 @@
 # UNRELEASED
 
+## Enhancements
+
+* Adds support for deleting `Stacks` that still have deployments through `ForceDelete` by @hashimoon [#969](https://github.com/hashicorp/go-tfe/pull/969)
+
 ## Bug Fixes
 
 * Fixed `RegistryNoCodeModules` method `UpgradeWorkspace` to return a `WorkspaceUpgrade` type. This resulted in a BREAKING CHANGE, yet the previous type was not properly decoded nor reflective of the actual API result by @paladin-devops [#955](https://github.com/hashicorp/go-tfe/pull/955)