Add changes file for Qt 5.9.6

Change-Id: Ib1bb8832b905ba0ac7c32743188d063b36b00fee
Reviewed-by: BogDan Vatra <bogdan@kdab.com>

dist/changes-5.9.6

+Qt 5.9.6 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.9.0 through 5.9.5.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+http://doc.qt.io/qt-5/index.html
+
+The Qt version 5.9 series is binary compatible with the 5.8.x series.
+Applications compiled for 5.8 will continue to run with 5.9.
+
+Some of the changes listed in this file include issue tracking numbers
+corresponding to tasks in the Qt Bug Tracker:
+
+https://bugreports.qt.io/
+
+Each of these identifiers can be entered in the bug tracker to obtain more
+information about a particular change.
+
+****************************************************************************
+*                              Qt 5.9.6 Changes                            *
+****************************************************************************
+
+ - This release contains only minor code improvements.