Qt Assistant files not found

[MTK358]

When I open Qt Assistant, it simply says "File not found!".

How do I install the help files? I'm using Arch Linux x86_64, if that matters.

[Urthas]

When I look for QtAssistant from within QtCreator using Help, this is what I get:

This module is no longer needed. Use the QtHelp module to integrate documentation into your application.

See also QtHelp.

[MTK358]

How does that help me?