Fix sphinx warnings

5 jobs for conda in 66 minutes and 55 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #120935
docker
build_linux_27

00:26:27

89.0%
passed #120936
docker
build_linux_36

00:26:13

89.0%
passed #120937
macosx
build_macosx_27

00:43:00

90.0%
passed #120972
macosx
build_macosx_36

00:23:50

90.0%
failed #120938
macosx
build_macosx_36

00:37:17

90.0%