Minor update to README wrt latest version released (1.5.1)

Author: cowtowncoder

README.md

@@ -52,7 +52,7 @@ To use ClassMate via Maven, include following dependency:
 <dependency>
   <groupId>com.fasterxml</groupId>
   <artifactId>classmate</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
 </dependency>
 ```