Revision control

++ ## Qt contribution guidelines
++
++ We welcome contributions to Qt!
++
++ Note that we cannot accept pull requests on GitHub. All contributions
++ to the Qt project are exclusively handled through the
++ [Gerrit code review system](https://codereview.qt-project.org).
++
++ See
++ [contribute.qt-project.org](https://contribute.qt-project.org/) to learn
++ more.