The build system v2 guide now references these examples with :example:
and :example_file: roles, so check_examples_documented.py no longer
expects them in the KNOWN_MISSING list. component_manager and the nested
import_prebuilt/prebuilt project are kept, since the guide does not link
them.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>