Repeated titles on many pages

[brian-rose]

Pages like this one:
https://foundations.projectpythia.org/numpy
have the title repeated twice.

The solution discussed in projectpythia-mystmd/cookbook-template#41 is to make sure that the top-level title is in the first cell of the notebook, and move the banner image below the title.

[brian-rose]

Pages affected:

• https://foundations.projectpythia.org/getting-started-github
  • Every page under that heading
• https://foundations.projectpythia.org/numpy
  • and all sub-pages
• https://foundations.projectpythia.org/matplotlib
  • and all sub-pages
• https://foundations.projectpythia.org/cartopy-1
• https://foundations.projectpythia.org/pandas-1
• https://foundations.projectpythia.org/netcdf-cf
• https://foundations.projectpythia.org/xarray
  • https://foundations.projectpythia.org/xarray-intro
  • https://foundations.projectpythia.org/dask-arrays-xarray