Docstring formatting for `TripolarGrid`

[glwagner]

It's a little wonky

help?> TripolarGrid
search: TripolarGrid

  TripolarGrid(arch = CPU(), FT::DataType = Float64;
                    size,
                    southermost_latitude = -80,
                    halo                 = (4, 4, 4),
                    radius               = R_Earth,
                    z                    = (0, 1),
                    north_poles_latitude = 45,
                    first_pole_longitude = 0)

  Constructs a tripolar grid on a spherical shell. NOTE: due to the requirements of the folding at the north edge of the domain,
  size[1] should be an even number.

[glwagner]

and first_pole_longitude description is mangled:

Keyword Arguments
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

    •  size: The number of cells in the (longitude, latitude, z) dimensions.

    •  southermost_latitude: The southernmost Center latitude of the grid. Default is -80.

    •  halo: The halo size in the (longitude, latitude, z) dimensions. Default is (4, 4, 4).

    •  radius: The radius of the spherical shell. Default is R_Earth.

    •  z: The z-coordinate range of the grid. Default is (0, 1).

    •  first_pole_longitude: The longitude of the first `north'' singularity. The second singularity will be located
       atfirstpolelongitude + 180ᵒ`.

    •  north_poles_latitude: The latitude of the ``north'' singularities.