esp-idf/docs/idf_extensions
..
build_system
README.md
__init__.py
esp_err_definitions.py
format_idf_target.py
gen_idf_tools_links.py
gen_toolchain_links.py
gen_version_specific_includes.py
include_build_file.py
kconfig_reference.py
link_roles.py
run_doxygen.py
util.py

README.md

See docs/en/contribute/add-ons-reference.rst (or in the IDF docs) for details.