Add gammaloop test banner and disclaimer in Readme.md

Author: ValentinHirschi

Readme.md

@@ -1,3 +1,16 @@
+
+
+# <h1 align="center"> Disclaimer </h1>
+
+This fork of the symbolica code is not meant to be used outside of the context of the [γLoop](https://github.com/alphal00p/gammaloop) project as it contains custom modifications that may not be suitable for a generic use.
+
+Make sure to instead use the original codebase available [here]("https://github.com/benruijl/symbolica").
+<p align="center">
+<a href="https://github.com/alphal00p/gammaloop"><img alt="Compatibility tests with gammaLoop" src="https://github.com/alphal00p/gammaloop/actions/workflows/gamma_loop_tests.yml/badge.svg?event=push"></a>
+</p>
+
+##
+
 <h1 align="center">
   <br>
   <picture>