README: Status Badge

Author: janbarasek

README.md

@@ -1,6 +1,8 @@
 Robust PHP math integral solver
 ===============================
 
+![Integrity check](https://github.com/mathematicator-core/integral-solver/workflows/Integrity%20check/badge.svg)
+
 Get instance of `IntegralSolver` and compute:
 
 ```php
@@ -14,4 +16,4 @@ All results can be renderer as LaTeX or returned as array of tokens for future c
 
 All dependencies you can get by [Package manager](https://github.com/baraja-core/package-manager).
 
-Fully compatible with `Nette 3.0` and `PHP 7.1`.
+Fully compatible with `Nette 3.0` and `PHP 7.1`.