Add download badge to README

Author: ErikKalkoken

README.md

@@ -5,6 +5,7 @@ A desktop app for viewing large JSON files.
 [![GitHub Release](https://img.shields.io/github/v/release/ErikKalkoken/janice)](https://github.com/ErikKalkoken/janice)
 [![build status](https://github.com/ErikKalkoken/janice/actions/workflows/ci-cd.yml/badge.svg)](https://github.com/ErikKalkoken/janice/actions/workflows/ci-cd.yml)
 [![GitHub License](https://img.shields.io/github/license/ErikKalkoken/janice)](https://github.com/ErikKalkoken/janice)
+[![GitHub Downloads (all assets, all releases)](https://img.shields.io/github/downloads/ErikKalkoken/janice/total)](https://github.com/ErikKalkoken/janice/releases)
 
 ## Contents