update search.maven.org url

Author: hboutemy

README.md

@@ -2,7 +2,7 @@ Plexus-IO
 =========
 
 [![Build Status](https://travis-ci.org/codehaus-plexus/plexus-io.svg?branch=master)](https://travis-ci.org/codehaus-plexus/plexus-io)
-[![Maven Central](https://img.shields.io/maven-central/v/org.codehaus.plexus/plexus-io.svg?label=Maven%20Central)](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.codehaus.plexus%22%20a%3A%plexus-io%22)
+[![Maven Central](https://img.shields.io/maven-central/v/org.codehaus.plexus/plexus-io.svg?label=Maven%20Central)](https://search.maven.org/artifact/org.codehaus.plexus/plexus-io)
 
 The current master is now at https://github.com/codehaus-plexus/plexus-io