fixed Java version in README.md

Author: bbottema

README.md

@@ -2,7 +2,7 @@
 [![Latest Release](https://img.shields.io/maven-central/v/org.simplejavamail/simple-java-mail.svg?style=flat)](https://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22org.simplejavamail%22%20AND%20v%3A%228.1.3%22) 
 [![Javadocs](https://img.shields.io/badge/javadoc-8.1.3-brightgreen.svg?color=brightgreen)](https://www.javadoc.io/doc/org.simplejavamail/maven-master-project) 
 [![Codacy](https://img.shields.io/codacy/grade/c7506663a4ab41e49b9675d87cd900b7.svg?style=flat)](https://app.codacy.com/gh/bbottema/simple-java-mail)
-![Java 1.7+](https://img.shields.io/badge/java-1.8+-lightgray.sv
+![Java 8+](https://img.shields.io/badge/java-8+-lightgray.svg)
 
 # Simple Java Mail #