README: add "Testing" section
README: add "Testing" section

Add new "Testing" section in README where we describe how meta-java
tests may be used.

Signed-off-by: Richard Leitner <0f2fdd4d2dfbb4dde6236fd550af0a2071b34781@skidata.com>

rehsack/meta-java,rehsack/meta-java,rehsack/meta-java,rehsack/meta-java,rehsack/meta-java