docs: add description and usage (#20)

Updated README with brief description and usage.

Author: droguljic

README.md

@@ -1,7 +1,13 @@
-# Orb
+# Security Orb [![CircleCI Build Status](https://circleci.com/gh/ExtensionEngine/pipeline-security-orb.svg?style=shield "CircleCI Build Status")](https://circleci.com/gh/ExtensionEngine/pipeline-security-orb) [![CircleCI Orb Version](https://badges.circleci.com/orbs/studion/security.svg)](https://circleci.com/developer/orbs/orb/studion/security) [![GitHub License](https://img.shields.io/badge/license-MIT-lightgrey.svg)](https://raw.githubusercontent.com/ExtensionEngine/pipeline-security-orb/master/LICENSE) [![CircleCI Community](https://img.shields.io/badge/community-CircleCI%20Discuss-343434.svg)](https://discuss.circleci.com/c/ecosystem/orbs)
 
-[![CircleCI Build Status](https://circleci.com/gh/ExtensionEngine/pipeline-security-orb.svg?style=shield "CircleCI Build Status")](https://circleci.com/gh/ExtensionEngine/pipeline-security-orb) [![CircleCI Orb Version](https://badges.circleci.com/orbs/studion/security.svg)](https://circleci.com/developer/orbs/orb/studion/security) [![GitHub License](https://img.shields.io/badge/license-MIT-lightgrey.svg)](https://raw.githubusercontent.com/ExtensionEngine/pipeline-security-orb/master/LICENSE) [![CircleCI Community](https://img.shields.io/badge/community-CircleCI%20Discuss-343434.svg)](https://discuss.circleci.com/c/ecosystem/orbs)
+An orb to facilitate security work within Studion CircleCI pipelines. Inspired by [ASH](https://github.com/awslabs/automated-security-helper).\
+Key features:
+- Audit dependencies for vulnerabilities, supports npm or pnpm
+- The default value of the package manager is picked from the environment
+- Detect secret leaks on the changeset or target a directory
+- Run a diff-aware static analysis tool to detect vulnerabilities
+- Opt for a full scan of the codebase when needed
 
-## Resources
+## Usage
 
-[CircleCI Orb Registry Page](https://circleci.com/developer/orbs/orb/studion/security) - The official registry page of this orb for all versions, executors, commands, and jobs described.
+See [the official registry page](https://circleci.com/developer/orbs/orb/studion/security) of this orb for guidelines and examples.