Adding architecture page + related images. (Checkmarx#1599)

docs/architecture.md

@@ -1,4 +1,29 @@
-## Architecture
+## Overview
 
-KICS Architecture was built from the ground up with cloud-native mindset.
-It was designed for automation, handles state carefully and assumes that the only constant is change.
+KICS is 100% open source is written in Golang using Open Policy Agent ([OPA](https://www.openpolicyagent.org/)).
+
+Golang speed, simplicity and reliability made it the perfect choice for writing KICS, while [Rego](https://www.openpolicyagent.org/docs/latest/policy-language/) as a query language, was a native choice to implement security queries. 
+
+So far have written 900+ ready-to-use queries that cover a wide range of vulnerabilities checks for AWS, GCP, Azure and other cloud providers. 
+
+## High Level Architecture
+
+KICS has a pluggable architecture with extensible pipeline of parsing IaC languages, which allows an easy integration of new IaC languages and queries.
+
+At a high very level, KICS is composed of the following main components: a command line interface, parser, queries execution engine,  IaC providers,  security queries, and results writer.
+
+- Command Line Interface => Provides CLI input to KICS.
+- Parser => responsible for parsing input IaC files (terraform and others)
+- IaC Providers => Converts IaC language into normalized JSON
+- Queries Execution Engine => applies REGO queries against normalized JSON
+- Security Queries => pre-built REGO queries for each security and misconfiguration
+- Writer => Writes results into JSON format
+
+<img src="../img/arch/high-level-arch.png" align="left">  
+
+
+## Execution Flow
+
+The sequence diagram below depicts interaction of the main KICS components:  
+<img src="../img/arch/exec-flow-1.png" align="left">  
+<img src="../img/arch/exec-flow-2.png" align="left">