Add changes file for 5.9.1

Change-Id: I07de9cad86a84fc0842cf81a27ea6da7c6272e2b
Reviewed-by: Karsten Heimrich <karsten.heimrich@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

dist/changes-5.9.1

+Qt 5.9.1 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.9.0.
+
+For more details, refer to the 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.
+
+General
+-------
+
+- [QTBUG-60926] Fixed building of qdoc documentation with a static Qt.
+
+androiddeployqt
+---------------
+
+- [QTBUG-60918] Fixed deployment of QtQuick.Controls 1 and QtQuick.Dialogs.
+
+macdeployqt
+-----------
+
+- [QTBUG-59609] Icon engines are now deployed.
+
+qtdiag
+------
+
+- Show more useful information about styles and platform themes.
+- [QTBUG-60962] Changed logic to determine name of ANGLE libraries by
+  existence.
+
+Qt Assistant
+------------
+
+- Fixed the build with qtwebkit.
+- Fixed availability of widget arrows in the search result.
+
+Qt Designer
+-----------
+
+- [QTBUG-61009] Fixed crash in "Go to slot" dialog when no signal is
+  selected.
+
+
+Qt Property Browser
+-------------------
+
+- Fixed build breakage when qreal is defined as float.
+
+windeployqt
+-----------
+
+- [QTBUG-61127] Added support of deploying Qt5GamePad with plugins.