Update documentation/manual/javaGuide/tutorials/zentasks/JavaGuide2.md

(documentation) Incorrect (relative) link to the test-data.yml file in the Java Zentasks tutorial. The file is needed for the subsequent test "fullTest" to pass correctly.
Merge pull request #751 from javaHelena/patch-2

Update documentation/manual/javaGuide/tutorials/zentasks/JavaGuide2.md