Fix sphinx warnings

12 jobs for highdb in 9 minutes and 27 seconds (queued for 9 seconds)
Status Job ID Name Coverage
  Build
passed #114768
conda-linux
build_linux_27

00:03:48

passed #114769
conda-linux
build_linux_35

00:03:48

passed #114770
conda-linux
build_linux_36

00:03:47

passed #114771
conda-macosx
build_macosx_27

00:04:47

passed #114772
conda-macosx
build_macosx_35

00:04:41

passed #114773
conda-macosx
build_macosx_36

00:04:39

 
  Test
passed #114774
conda-linux
test_linux_27

00:03:49

passed #114775
conda-linux
test_linux_35

00:03:55

passed #114776
conda-linux
test_linux_36

00:03:54

passed #114777
conda-macosx
test_macosx_27

00:04:32

passed #114778
conda-macosx
test_macosx_35

00:04:35

passed #114779
conda-macosx
test_macosx_36

00:04:34