Add changes-5.1.1 file

Change-Id: I056aba05ab8e3e1c8ea9edde1a893bbade3d379a
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>

dist/changes-5.1.1

+Qt 5.1.1 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.1.0.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+  http://qt-project.org/doc/qt-5.1/
+
+The Qt version 5.1 series is binary compatible with the 5.0.x series.
+Applications compiled for 5.0 will continue to run with 5.1.
+
+Some of the changes listed in this file include issue tracking numbers
+corresponding to tasks in the Qt Bug Tracker:
+
+  http://bugreports.qt-project.org/
+
+Each of these identifiers can be entered in the bug tracker to obtain more
+information about a particular change.
+
+
+****************************************************************************
+*                           General                                        *
+****************************************************************************
+
+ - This release contains only minor code improvements.