Readme update

Author: denis256

README.md

@@ -4,6 +4,16 @@
 
 ## Overview
 
+Prior to the introduction of IAC Engines, Terragrunt directly wrapped Terraform, and then Terraform CLI commands in order to orchestrate IAC updates in a scalable, and maintainable manner.
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+Over time, the Terragrunt codebase has grown in complexity, and the need for a more modular, and maintainable approach to managing IAC updates has become apparent. The Terraform Engine is the first Terragrunt IAC Engine implementation, and is designed to demonstrate how IAC updates can be delegated to a separate plugin that can be maintained independently of the Terragrunt codebase.
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+As it stands, this engine simply reproduces the existing behavior of Terragrunt, mediated by RPC calls to a plugin running locally. Note that the design of the IAC Engine system is intended to be more flexible in that it allows for myriad implementations of IAC engines, including those that may execute IAC updates in a remote environment, or include additional functionality beyond what is currently available by directly calling Terraform CLI commands.
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+We hope that this engine will inspire you to experiment and create your own IAC Engine implementations, and we look forward to seeing what you come up with!
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+For more information, see the [Terragrunt IAC Engine RFC](https://github.com/gruntwork-io/terragrunt/issues/3103).
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 ## Automated Release Process
 
 To initiate the release process, create a pre-release named using the following naming convention: `vx.y.z-rcdateincrement`, with the appropriate corresponding tag.