[FEA] Please include header names in libcudf documentation

[dagardner-nv]

Is your feature request related to a problem? Please describe.
Edit: I just noticed I can get at the libcudf (Doxygen?) documentation with https://docs.rapids.ai/api/libcudf and that version of the docs includes the header info.

The libcudf documentation does not always indicate what header(s) are needed for a given class/function.

ex: https://docs.rapids.ai/api/cudf/stable/libcudf_docs/api_docs/scalar_factories/

I would like to use the make_string_scalar method however the header is not documented anywhere.

At the top of https://docs.rapids.ai/api/cudf/stable/libcudf_docs/api_docs/scalar_classes/
it does mention #include <scalar.hpp> however from an end-user perspective the include would be #include <cudf/scalar/scalar.hpp>

Describe the solution you'd like
Document the headers for each class/method

Describe alternatives you've considered
https://docs.rapids.ai/api/libcudf

Additional context
n/a