Add changes file for Qt 5.11.0

Change-Id: I0acf6b01b1a9e3bbb9a9d116b7f6dc273b2f2861
Reviewed-by: Liang Qi <liang.qi@qt.io>

dist/changes-5.11.0

+Qt 5.11 introduces many new features and improvements as well as bugfixes
+over the 5.10.x series. 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 5.11 series is binary compatible with the 5.10.x series.
+Applications compiled for 5.10 will continue to run with 5.11.
+
+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 5.11.0 Changes                             *
+****************************************************************************
+
+Third-Party Code
+----------------
+
+ - Bundled libwebp was updated to version 0.6.1
+
+Native Darwin jp2 and heic handlers
+-----------------------------------
+
+ - iOS support fixed