Updated README.md

README.md

@@ -64,8 +64,15 @@ We literally have [*hundreds of terraform modules*][terraform_modules] that are
 ## Usage
 
 
-**IMPORTANT:** The `master` branch is used in `source` just as an example. In your code, do not pin to `master` because there may be breaking changes between releases.
-Instead pin to the release tag (e.g. `?ref=tags/x.y.z`) of one of our [latest releases](https://github.com/cloudposse/terraform-aws-ecs-web-app/releases).
+**IMPORTANT:** We do not pin modules to versions in our examples because of the
+difficulty of keeping the versions in the documentation in sync with the latest released versions.
+We highly recommend that in your code you pin the version to the exact version you are
+using so that your infrastructure remains stable, and update versions in a
+systematic way so that they do not catch you by surprise.
+
+Also, because of a bug in the Terraform registry ([hashicorp/terraform#21417](https://github.com/hashicorp/terraform/issues/21417)),
+the registry shows many of our inputs as required when in fact they are optional.
+The table below correctly indicates which inputs are required.
 
 
 For a complete example, see [examples/complete](examples/complete).
@@ -470,7 +477,7 @@ In general, PRs are welcome. We follow the typical "fork-and-pull" Git workflow.
 
 ## Copyright
 
-Copyright © 2017-2020 [Cloud Posse, LLC](https://cpco.io/copyright)
+Copyright © 2017-2021 [Cloud Posse, LLC](https://cpco.io/copyright)