update readme with icons

Author: Laeborg

README.md

@@ -1,5 +1,9 @@
 # CS2 Case Opening Analyzer
 
+[![Firefox Add-on](https://img.shields.io/badge/Firefox-Add--on-FF7139?style=flat-square&logo=firefox-browser&logoColor=white)](https://addons.mozilla.org/en-US/firefox/addon/cs2-case-opening-analyzer/)
+[![GitHub release (latest by date)](https://img.shields.io/github/v/release/laeborg/caseanalyzer-firefox?style=flat-square)](https://github.com/laeborg/caseanalyzer-firefox/releases)
+[![GitHub license](https://img.shields.io/github/license/laeborg/caseanalyzer-firefox?style=flat-square)](https://github.com/laeborg/caseanalyzer-firefox/blob/main/LICENSE)
+
 A Firefox extension that analyzes your CS2 Case Openings directly from your Steam Inventory History page.
 
 ![Screenshot showing the analyzer overlay](screenshot.png)