added another link

Signed-off-by: Adrian Plata <adrian.plata@docker.com>

docs/spec/deprecated-schema-v1.md

@@ -15,4 +15,5 @@ inexhaustive list of possible methods to help update your image.
 Update the `FROM` statement in your `Dockerfile`. If your image manifest is
 out-of-date, there is a chance the image pulled from your `FROM` statement in
 your `Dockerfile` is also out-of-date. See the [Dockerfile reference](https://docs.docker.com/engine/reference/builder/#from)
+and the [Dockerfile best practices guide](https://docs.docker.com/develop/develop-images/dockerfile_best-practices/)
 for more information on how to update your `Dockerfile`.