Seems like I just can't find the QDoc executable.
I downloaded Qt 5.11.1.
Do I need to download QDoc separately?
I checked the docs, but all it says is:
To run qdoc from the command line, give it the name of a configuration file:
$ ../../bin/qdoc ./config.qdocconf
Which doesn't help much for finding the file itself.
If you're using mingw: that build of Qt is missing qdoc for MinGW builds.
See https://wiki.qt.io/Qt_5.11.1_Known_Issues and https://bugreports.qt.io/browse/QTBUG-68064.
You'll need to download qdoc from source and build it (or use an older version potentially).