CHANGELOG for 2.16.0 (#961)

* Adding changelog entry for PR #960

* Updated CHANGELOG for 2.16.0 release, using `go-changelog`

1. `go install github.com/hashicorp/go-changelog/cmd/changelog-build@latest`
2. `changelog-build -changelog-template .changelog.tmpl -entries-dir .changelog -last-release $(git describe --tags --abbrev=0) -note-template .changelog-note.tmpl -this-release HEAD`

* Tweaking changelog entry format

.changelog/960.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+helper/resource: Updated version of [hc-install](github.com/hashicorp/hc-install) in response to change in HashiCorp Release API [sending back a different `Content-Type` header](https://github.com/hashicorp/hc-install/issues/56). This was causing failures when the SDK attempted to install Terraform.
+```

CHANGELOG.md

@@ -1,3 +1,11 @@
+# 2.16.0 (May 10, 2022)
+
+ENHANCEMENTS:
+* helper/resource: Added error logging before failing tests, so errors are visible in test output and any separate log file ([#958](https://github.com/hashicorp/terraform-plugin-sdk/issues/958))
+
+BUG FIXES:
+* helper/resource: Updated version of [hc-install](github.com/hashicorp/hc-install) in response to change in HashiCorp Release API [sending back a different `Content-Type` header](https://github.com/hashicorp/hc-install/issues/56). This was causing failures when the SDK attempted to install Terraform. ([#960](https://github.com/hashicorp/terraform-plugin-sdk/issues/960))
+
 # 2.15.0 (May 4, 2022)
 
 FEATURES: