code: def _insert_common_sphinx_configs(c, *, project_name):
      
      c['project'] = project_name
  
      # The suffix(es) of source filenames.
      # You can specify multiple suffix as a list of string:
      c['source_suffix'] = '.rst'
  
      # The encoding of source files.
      c['source_encoding'] = 'utf-8-sig'
  
      # The master toctree document.
      c['master_doc'] = 'index'
  
      # Configure figure numbering
      c['numfig'] = True
      c['numfig_format'] = {'figure': 'Figure %s',
                            'table': 'Table %s',
                            'code-block': 'Listing %s'}
  
      # The reST default role (used for this markup: `text`)
      c['default_role'] = 'obj'
  
      # This is added to the end of RST files - a good place to put substitutions
      # to be used globally.
      c['rst_epilog'] = """
  .. _Astropy: http://astropy.org
      """
  
      # A list of warning types to suppress arbitrary warning messages. We mean
      # to override directives in
      # astropy_helpers.sphinx.ext.autodoc_enhancements, thus need to ignore
      # those warning. This can be removed once the patch gets released in
      # upstream Sphinx (https://github.com/sphinx-doc/sphinx/pull/1843).
      # Suppress the warnings requires Sphinx v1.4.2
      c['suppress_warnings'] = ['app.add_directive', ]
  
      return c
docs: Add common core Sphinx configurations to the state.