new_contents: """Sphinx/docutils extensions for LSST DM documentation."""
  """Sphinx/docutils extensions for LSST DM documentation.
  
  Enable these extension by adding `documenteer.sphinxext` to your
  extensions list in :file:`conf.py`::
  
      extensions = [
         # ...
         'documenteer.sphinxext'
      ]
  """
  
subject: Add documenteer.sphinxext subpackage