[toolchain] Fix sphinx warnings

4 jobs for autodoc-default-flags-is-removed in 21 minutes and 57 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Build
passed #216819
docker-build
build_linux_36

00:15:01

64.0%
passed #216820
docker-build
build_linux_37

00:14:52

64.0%
passed #216817
macosx
build_macosx_36

00:21:57

64.0%
passed #216818
macosx
build_macosx_37

00:14:56

64.0%