It looks like the documentation build targets (tfm_docs_userguide_html and tfm_docs_userguide_pdf) are not available in your CMake configuration. Here are a few things you can check:

1. Ensure Dependencies Are Installed – Make sure you have all necessary dependencies like Doxygen, Sphinx, and LaTeX (for PDF generation) installed.
2. Verify CMake Configuration – Run cmake --build cmake_doc --target help to list available targets and check if the documentation targets are present.
3. Check the Build Configuration – Try running cmake --preset=doc if the TF-M build system provides a preset for documentation.
4. Manually Generate Docs – If the automatic build fails, you may need to generate documentation manually using doxygen and sphinx-build.