Doc: Fix linking to 'Versionless commands'

The qt_target_qml_from_lottie CMake command documentation uses a macro
\versionlessCMakeCommandsNote, which in turn tries to link to Qt CMake
documentation. Add dependency to `qtcmake` to make the linking work.

Pick-to: 6.12
Change-Id: I89a4210a0be8578d8bbcc9f6401e49aae24833d0
Reviewed-by: Alexei Cazacov <alexei.cazacov@qt.io>