Clarify how interface library is installed

My question is a much simpler version of a question from 2020: INTERFACE library not getting installed and no error reported.

In Step 5 of the tutorial, the interface library tutorial_compiler_flags is a member of the list installable_libs, but no corresponding artifact seems to be installed. The documentation seems clear enough:

An interface library with no source files is not included as a target in the generated buildsystem. However, it may have properties set on it and it may be installed and exported.

Setting the properties is working - they turn up in the Visual Studio projects on Windows and in the Makefiles on Linux.

Should something be installed for the interface library?

CMake 3.28, min version 3.15

A target of just flags is only going to show up in the install(EXPORT) part of the install as there’s nothing else to it. The tutorial could probably explain this better.