DOC: Fix API strings for documentation

[KCollins]

Related to #46 , #47

Example from conjugate_map:

def calc_mlat_rings(mlats, ut=dt.datetime.now(tz=dt.timezone.utc),
                    is_verbose=False, is_saved=False):

    """Calculate the geographic latitudes and longitudes of a circle of points
    for a list of magnetic latitudes.

    Parameters
    ----------
    mlats       : np.array
            List of magnetic latitudes
    ut          : dt.datetime
            Datetime used in AACGMv2 conversion;
            by default, ut=dt.datetime.now(tz=dt.timezone.utc)
    is_verbose  : boolean
            If set to True/1, prints debugging text.
    is_saved    : boolean
            If is_saved == True, saves .gpx versions.
                        to local output directory

    Returns
    -------
    mlats_dct: dict
        Dictionary with geographic latitude and longitude
        points for each of the specified magnetic latitudes.

    Example Use
    ------------
    Saves .gpx magnetic graticules for 1 January 2020 every 5
    degrees latitude::

        rings = calc_mlat_rings(list(range(-90, 90, 5)), ut =
                        dt.datetime(2020, 1, 1), is_saved = True)

    """
    """