docs: def get_project_content_commit_date(root_dir='.', exclusions=None):
      """Get the datetime for the most recent commit to a project that
      affected Sphinx content.
  
      *Content* is considered any file with one of these extensions:
  
      - ``rst`` (README.rst and LICENSE.rst are excluded)
      - ``ipynb``
      - ``png``
      - ``jpeg``
      - ``jpg``
      - ``svg``
      - ``gif``
  
      This function allows project infrastructure and configuration files to be
      updated without changing the timestamp.
  
      Parameters
      ----------
      root_dir : `str`, optional
          Root directory. This is the current working directory by default.
      exclusions : `list` of `str`, optional
          List of file paths or directory paths to ignore.
  
      Returns
      -------
      commit_date : `datetime.datetime`
          Datetime of the most recent content commit.
  
      Raises
      ------
      RuntimeError
          Raised if no content files are found.
      """
      logger = logging.getLogger(__name__)
  
      # Supported 'content' extensions
      extensions = ('rst', 'ipynb', 'png', 'jpeg', 'jpg', 'svg', 'gif')
  
      content_paths = []
      for extname in extensions:
          content_paths += get_filepaths_with_extension(
              extname,
              root_dir=root_dir)
  
      # Known files that should be excluded; lower case for comparison
      exclude = Matcher(exclusions if exclusions
                        else ['readme.rst', 'license.rst'])
  
      # filter out excluded files
      content_paths = [p for p in content_paths
                       if not (exclude(p) or exclude(p.split(os.path.sep)[0]))]
      logger.debug('Found content paths: {}'.format(', '.join(content_paths)))
  
      if not content_paths:
          raise RuntimeError('No content files found in {}'.format(root_dir))
  
      commit_datetimes = []
      for filepath in content_paths:
          try:
              datetime = read_git_commit_timestamp_for_file(
                  filepath,
                  repo_path=root_dir)
              commit_datetimes.append(datetime)
          except IOError:
              logger.warning(
                  'Could not get commit for {}, skipping'.format(filepath))
  
      if not commit_datetimes:
          raise RuntimeError('No content commits could be found')
  
      latest_datetime = max(commit_datetimes)
  
      return latest_datetime