docs: Updated version of module to use for Terraform 0.12 users

Author: antonbabenko

README.md

@@ -11,7 +11,7 @@ Doing serverless with Terraform? Check out [serverless.tf framework](https://ser
 
 Terraform 0.13. Pin module version to `~> v4.0`. Submit pull-requests to `master` branch.
 
-Terraform 0.12. Pin module version to `3.4.0` (or older). Submit pull-requests to `terraform012` branch.
+Terraform 0.12. Pin module version to `3.5.0` (or older). Submit pull-requests to `terraform012` branch.
 
 Terraform 0.11. Pin module version to `~> v1.0`.