Fix maven badge

Author: pith

README.md

@@ -1,6 +1,6 @@
 # SeedStack validation add-on
 
-[![Build status](https://travis-ci.org/seedstack/validation-addon.svg?branch=master)](https://travis-ci.org/seedstack/validation-addon) [![Coverage Status](https://coveralls.io/repos/seedstack/validation-addon/badge.svg?branch=master)](https://coveralls.io/r/seedstack/validation-addon?branch=master) [![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.seedstack/seed-validation/badge.svg?style=flat)](https://maven-badges.herokuapp.com/maven-central/org.seedstack/seed-validation)
+[![Build status](https://travis-ci.org/seedstack/validation-addon.svg?branch=master)](https://travis-ci.org/seedstack/validation-addon) [![Coverage Status](https://coveralls.io/repos/seedstack/validation-addon/badge.svg?branch=master)](https://coveralls.io/r/seedstack/validation-addon?branch=master) [![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.seedstack.addons.validation/validation/badge.svg?style=flat)](https://maven-badges.herokuapp.com/maven-central/org.seedstack.addons.validation/validation)
 
 Official validation integration for SeedStack.