Fix documentation for Transformer item.
Fix documentation for Transformer item.

In the code example, we go against our own advice by not closing the
file explicitly.

Change-Id: Ie5995d8ca99f636db822c18d93813cafaaf9f77e
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@digia.com>

villytiger/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,Distrotech/qbs,villytiger/qbs,villytiger/qbs,villytiger/qbs,Distrotech/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,Distrotech/qbs,Distrotech/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,villytiger/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,Distrotech/qbs,villytiger/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,Distrotech/qbs,qt-labs/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs