Doc: Updated url variable in qdocconf files.
Doc: Updated url variable in qdocconf files.

In 5.2, the HTML output is in a flatter structure and when they are
hosted in qt-project.org/doc, the documentation will be found at
http://qt-project.org/doc/qt-$QT_VER

The url variable is used by projects outside of Qt 5 which need
to link to Qt 5 documentation, such as Qt Creator.

Task-number: QTBUG-34584
Change-Id: I76ca42d3d9f125588ae72003d85b27ef1f9cee2d
Reviewed-by: Topi Reiniö <92400b03a70fe3119347f89b476f73d34ae93598@digia.com>
Reviewed-by: aavit <7b3193bdca3a57b9140f9c882d4fe8f629e8932f@digia.com>
Reviewed-by: Leena Miettinen <885fda02d52616fec24ed5fed9b3f0568fce3ead@digia.com>

kobolabs/qtimageformats,kobolabs/qtimageformats,kobolabs/qtimageformats,kobolabs/qtimageformats