Mention defaulting to BuildKit (#12505)

* Mention defaulting to BuildKit

* Mention defaulting to BuildKit

* Update docker-for-mac/release-notes.md

Co-authored-by: Usha Mandya <[email protected]>

* Update docker-for-mac/release-notes.md

Co-authored-by: Usha Mandya <[email protected]>

* Update release-notes.md

Co-authored-by: Usha Mandya <[email protected]>

Author: stephen-turner

docker-for-mac/release-notes.md

@@ -52,6 +52,12 @@ This page contains information about the new features, improvements, known issue
 - The Docker Dashboard displays a tip once a week.
 - Docker Desktop uses iTerm2 to launch the terminal on the container if it is installed. Otherwise, it launches the default Terminal.App. [docker/roadmap#98](https://github.com/docker/roadmap/issues/98)
 - Add experimental support to use the new Apple Virtualization framework (requires macOS Big Sur 11.1 or later)
+- BuildKit is now the default builder for all users, not just for new installations. To turn this setting off, go to **Preferences** > **Docker Engine** and add the following block to the Docker daemon configuration file:
+```json
+"features": {
+    "buildkit": false
+}
+```
 
 ### Upgrades
 

docker-for-windows/release-notes.md

@@ -45,6 +45,12 @@ This page contains information about the new features, improvements, known issue
 
 - The Docker Dashboard opens automatically when you start Docker Desktop.
 - The Docker Dashboard displays a tip once a week.
+- BuildKit is now the default builder for all users, not just for new installations. To turn this setting off, go to **Settings** > **Docker Engine** and add the following block to the Docker daemon configuration file:
+```json
+"features": {
+    "buildkit": false
+}
+```
 
 ### Upgrades
 
@@ -201,7 +207,7 @@ Docker Desktop 2.4.0.0 contains a Kubernetes upgrade. Your local Kubernetes clus
 
 - [Docker Compose CLI - 0.1.18](https://github.com/docker/compose-cli), enabling use of volumes with Compose and the Cloud through ECS and ACI.
 - Docker introduces the new Images view in the Docker Dashboard. The images view allows users to view the Hub images, pull them and manage their local images on disk including cleaning up unwanted and unused images. To access the new Images view, from the Docker menu, select **Dashboard** > **Images**.
-- Docker Desktop now enables BuildKit by default after a reset to factory defaults. To revert to the old `docker build` experience, go to **Preferences** > **Docker Engine** and then disable the BuildKit feature.
+- Docker Desktop now enables BuildKit by default after a reset to factory defaults. To revert to the old `docker build` experience, go to **Settings** > **Docker Engine** and then disable the BuildKit feature.
 - [Amazon ECR Credential Helper](https://github.com/awslabs/amazon-ecr-credential-helper/releases/tag/v0.4.0)
 
 ### Upgrades