Add changes file for Qt 5.15.2

- 0dfebafe57 Add changes file for Qt 5.15.1
+ 09854eefb2 QLowEnergyController (Darwin) - restore the logic we had in 5.12
+ 8e624270b7 Bump version
+ b8b8d881ba Add changes file for Qt 5.12.10

Change-Id: I2a33bddac57bb71a07850a1baee7aa30d50e615d
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit ca6cc606d9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

dist/changes-5.15.2

@@ -0,0 +1,24 @@
+Qt 5.15.2 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.15.1.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+  https://doc.qt.io/qt-5.15/index.html
+
+The Qt version 5.15 series is binary compatible with the 5.14.x series.
+Applications compiled for 5.14 will continue to run with 5.15.
+
+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 5.15.2                                   *
+****************************************************************************
+
+This release only contains minor changes.