Using idf_component_register is the preferred method for creating new
components for cmakev2. This approach ensures compatibility with both
versions of the build system. The KCONFIG and KCONFIG_PROJBUILD options
have been removed from the API documentation, but are retained in code
in case a cmakev1 component uses these options to warn about
incompatibility. Also remove a note about `project_include.cmake`,
because cmakev2 includes all project_include files.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>
997cd81675