Additional CHANGELOG note for v1.6.0 (#257)

Reference: #223
Reference: #237
Reference: #256

Post-release update to the v1.6.0 CHANGELOG to capture now-known situations that would affect existing provider testing. This update ensures developers upgrading to v1.6.0 will receive the latest guidance and the guidance will remain for this version after future releases. If approved and merged, the v1.6.0 GitHub Release description will also be updated with the same additional content.

Author: bflad

.changes/1.6.0.md

@@ -4,6 +4,7 @@ NOTES:
 
 * all: This Go module has been updated to Go 1.20 per the [Go support policy](https://go.dev/doc/devel/release#policy). It is recommended to review the [Go 1.20 release notes](https://go.dev/doc/go1.20) before upgrading. Any consumers building on earlier Go versions may experience errors. ([#180](https://github.com/hashicorp/terraform-plugin-testing/issues/180))
 * helper/resource: Configuration based `TestStep` now include post-apply plan checks for output changes in addition to resource changes. If this causes unexpected new test failures, most `output` configuration blocks can be likely be removed. Test steps involving resources and data sources should never need to use `output` configuration blocks as plan and state checks support working on resource and data source attributes values directly. ([#234](https://github.com/hashicorp/terraform-plugin-testing/issues/234))
+* helper/resource: Implicit `terraform refresh` commands during each `TestStep` have been removed to fix plan check and performance issues, which can cause new test failures when testing schema changes (e.g. state upgrades) that have a final `TestStep` with `PlanOnly: true`. Remove `PlanOnly: true` from the final `TestStep` to fix affected tests which will ensure that updated schema changes are applied to the state before attempting to automatically destroy resources. ([#223](https://github.com/hashicorp/terraform-plugin-testing/issues/223))
 
 FEATURES:
 

CHANGELOG.md

@@ -4,6 +4,7 @@ NOTES:
 
 * all: This Go module has been updated to Go 1.20 per the [Go support policy](https://go.dev/doc/devel/release#policy). It is recommended to review the [Go 1.20 release notes](https://go.dev/doc/go1.20) before upgrading. Any consumers building on earlier Go versions may experience errors. ([#180](https://github.com/hashicorp/terraform-plugin-testing/issues/180))
 * helper/resource: Configuration based `TestStep` now include post-apply plan checks for output changes in addition to resource changes. If this causes unexpected new test failures, most `output` configuration blocks can be likely be removed. Test steps involving resources and data sources should never need to use `output` configuration blocks as plan and state checks support working on resource and data source attributes values directly. ([#234](https://github.com/hashicorp/terraform-plugin-testing/issues/234))
+* helper/resource: Implicit `terraform refresh` commands during each `TestStep` have been removed to fix plan check and performance issues, which can cause new test failures when testing schema changes (e.g. state upgrades) that have a final `TestStep` with `PlanOnly: true`. Remove `PlanOnly: true` from the final `TestStep` to fix affected tests which will ensure that updated schema changes are applied to the state before attempting to automatically destroy resources. ([#223](https://github.com/hashicorp/terraform-plugin-testing/issues/223))
 
 FEATURES: