Added a change log for Qt 5.6

...and linked to it from the related files

This is mostly a template for now, but I wanted to add the
Qt Serial Bus Module.

Change-Id: I3a612b4ddaf7961374cbdf6845093f7b711a86f7
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>