Update README.md with instsall instructions for ArchLinux / Manjaro (#…

…1011)

Adding installation instructions for ArchLinux / Manjaro User
Adding build icon from AUR (Arch User Repository)

README.md

@@ -4,6 +4,7 @@
 [![License: Apache 2.0](https://img.shields.io/badge/license-Apache%202-blue)](https://github.com/accurics/terrascan/blob/master/LICENSE)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://github.com/accurics/terrascan/pulls)
 ![CI](https://github.com/accurics/terrascan/workflows/build/badge.svg)
+[![AUR package](https://repology.org/badge/version-for-repo/aur/terrascan.svg)](https://repology.org/project/terrascan/versions)
 [![codecov](https://codecov.io/gh/accurics/terrascan/branch/master/graph/badge.svg)](https://codecov.io/gh/accurics/terrascan)
 [![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)
@@ -51,6 +52,14 @@ $ install terrascan /usr/local/bin && rm terrascan
 $ terrascan
 ```
 
+#### Install on ArchLinux / Manjaro via `AUR`
+
+ArchLinux and Manjaro users can install by:
+
+```
+yay -S terrascan
+```
+
 #### Install via `brew`
 
 [Homebrew](https://brew.sh/) users can install by: