[Development] "classes" toc entry in Qt5 qch docs from assistant

[Alan Ezust]

In the "contents" tab, there is a tree node for "classes" just below
"qt reference documentation".
When I click on it, it says
The page could not be found. 'qthelp://com.trolltech.qt.500/qdoc/'
There is another page that has all classes.
qthelp://com.trolltech.qt.500/qdoc/classes.html
I think clicking on "classes" should open this page above.