Add changes file for 2.5.2

Change-Id: Ied30b5449b638ff198d9fe8296aa5a0f38c9075e
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@nokia.com>

dist/changes-2.5.2

+Qt Creator version 2.5.2 contains bug fixes.
+
+The most important changes are listed in this document. For a complete
+list of changes, see the Git log for the Qt Creator sources that
+you can check out from the public Git repository. For example:
+
+git clone git://gitorious.org/qt-creator/qt-creator.git
+git log --cherry-pick --pretty=oneline v2.5.1...v2.5.2
+
+Platform Specific
+
+Windows
+   * Fixed resource leak leading to regular crashes (QTCREATORBUG-7385)