doc: add homebrew badge (#714)

Signed-off-by: Rui Chen <rui@chenrui.dev>

README.md

@@ -8,6 +8,7 @@
 [![community](https://img.shields.io/discourse/status?server=https%3A%2F%2Fcommunity.accurics.com)](https://community.accurics.com)
 [![Documentation Status](https://readthedocs.com/projects/accurics-terrascan/badge/?version=latest)](https://docs.accurics.com/projects/accurics-terrascan/en/latest/?badge=latest)
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg)](code_of_conduct.md)
+[![Homebrew](https://img.shields.io/badge/dynamic/json.svg?url=https://formulae.brew.sh/api/formula/terrascan.json&query=$.versions.stable&label=homebrew)](https://formulae.brew.sh/formula/terrascan)
 
 Terrascan detects security vulnerabilities and compliance violations across your Infrastructure as Code. Mitigate risks before provisioning cloud native infrastructure. Run locally or integrate with your CI\CD.