docs: Java 7 is the target (#24)
@rfscholte update from java 6
diff --git a/readme.md b/readme.md
index f78e685..4050f9d 100644
--- a/readme.md
+++ b/readme.md
@@ -54,7 +54,7 @@
+ Create a branch from where you want to base your work (this is usually the master branch).
Push your changes to a branch in your fork of the repository.
+ Make commits of logical units.
-+ You can use version 9 of Java, but be aware that the code has target of version 6.
++ You can compile with JDK 7 or later, but the code targets Java 7. For example, you cannot use lambdas.
+ Respect the original code style: by using the same [codestyle][code-style],
patches should only highlight the actual difference, not being disturbed by any formatting issues:
+ Only use spaces for indentation.
