updates release notes

CHANGELOG.md

@@ -1,7 +1,11 @@
 # Changelog
 
 ## 1.0.0 (UNRELEASED)
-Major updates to Terrascan and the underlying architecture.
+Major updates to Terrascan and the underlying architecture including:
+* Pluggable architecture written in Golang. We updated the architecture to be easier to extend Terrascan with additional IaC languages and support policies for different cloud providers and cloud native tooling.
+* Server mode. This allows Terrascan to be executed as a server and use it's API to perform static code analysis
+* Notifications hooks. Will be able to integrate for notifications to external systems (e.g. email, slack, etc.)
+* Uses OPA policy engine and policies written in Rego.
 
 ## 0.2.3 (2020-07-23)
 * Introduces the '-f' flag for passing a list of ".tf" files for linting and the '--version' flag.