docs: fix Stryker badge (#298)

readme.md

@@ -7,7 +7,7 @@
 [![npm](https://img.shields.io/npm/v/@xmldom/xmldom?style=flat-square)](https://www.npmjs.com/package/@xmldom/xmldom)
 [![bug issues](https://img.shields.io/github/issues/xmldom/xmldom/bug?color=red&style=flat-square)](https://github.com/xmldom/xmldom/issues?q=is%3Aissue+is%3Aopen+label%3Abug)
 [!["help wanted" issues](https://img.shields.io/github/issues/xmldom/xmldom/help%20wanted?color=darkgreen&style=flat-square)](https://github.com/xmldom/xmldom/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22)
-[![Mutation testing badge](https://img.shields.io/endpoint?style=flat&url=https%3A%2F%2Fbadge-api.stryker-mutator.io%2Fgithub.com%2Fxmldom%2Fxmldom%2Fmaster)](https://dashboard.stryker-mutator.io/reports/github.com/xmldom/xmldom/master)
+[![Mutation report](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fbadge-api.stryker-mutator.io%2Fgithub.com%2Fxmldom%2Fxmldom%2Fmaster)](https://dashboard.stryker-mutator.io/reports/github.com/xmldom/xmldom/master)
 
 
 xmldom is a javascript [ponyfill](https://ponyfill.com/) to provide the following APIs [that are present in modern browsers](https://caniuse.com/xml-serializer) to other runtimes: