[Development] Preventing link rot in Qt docs

[Sze Howe Koh]

In the transition from Qt 5.11 to Qt 5.12, some doc URLs have changed,
for example:

    https://doc.qt.io/qt-5/android-support.html ->
https://doc.qt.io/qt-5/android.html
    https://doc.qt.io/qt-5/androidgs.html ->
https://doc.qt.io/qt-5/android-getting-started.html

While I do like the new URLs better, the old URLs now give Error 404.
This is a problem because the Qt docs are heavily cited in the forums,
the wiki, and external sites like StackOverflow. Search engines also
take time to catch up, e.g. the top two results are currently dead at
https://www.google.com/search?q=site%3Adoc.qt.io%2Fqt-5+android

Is it feasible to make doc redirections an integral part of the
release process? Diffing the list of HTML files produced by qdoc
should help a lot.


Regards,
Sze-Howe