Add badge to show number of project installations

Author: clue

README.md

@@ -2,6 +2,7 @@
 
 [![CI status](https://github.com/clue-access/framework-x/workflows/CI/badge.svg)](https://github.com/clue-access/framework-x/actions)
 [![code coverage](https://img.shields.io/badge/code%20coverage-100%25-success)](#tests)
+[![installs on Packagist](https://img.shields.io/packagist/dt/clue/framework-x?color=blue&label=installs%20on%20Packagist)](https://packagist.org/packages/clue/framework-x)
 
 Framework X – the simple and fast micro framework for building reactive web applications that run anywhere.