Readme and example not accurate

[eimrek]

Hi @dou-du

Since moving to anywidget, i changed the python interface to reflect the underlying javascript code, see

widget-bandsplot/src/widget_bandsplot/__init__.py

Lines 13 to 34 in c341a59

	class BandsPlotWidget(anywidget.AnyWidget):
	_esm = pathlib.Path(__file__).parent / "static" / "widget.js"
	_css = pathlib.Path(__file__).parent / "static" / "widget.css"
	bands = tl.List([]).tag(sync=True)
	dos = tl.Dict().tag(sync=True)
	energy_range = tl.List([-10.0, 10.0]).tag(sync=True)
	dos_range = tl.List([]).tag(sync=True)
	bands_color = tl.List([]).tag(sync=True)
	# Formatting settings:
	# * showFermi
	# * showLegend
	# * bandsYlabel
	format_settings = tl.Dict({}).tag(sync=True)
	def __init__(
	self,
	**kwargs,
	):
	"""The traitlets defined above are possible kwargs."""
	super().__init__(**kwargs)

E.g. plot_fermilevel and show_legend are now inside the format_settings dict.

More precisely:

• The current example notebook and the readme are out of date.

• Additionally, the readme states that we use a JSON schema for the PDOS, but that is not true any more.

• The demo gif is also outdated. it might confuse users that don't get the same visual output. But perhaps it's fine to keep.

• In general, i think it doesn't make sense to duplicate the usage examples in the README and also in the example notebook. it just a burden to keep the synchronized. But i'm not strongly opposed to it.

• Also i think the extra information in the example notebook could be reduced considerably, e.g. it doesn't make sense to first write in the markdown about

  with open('./data/Si_bands.json', 'r') as file:
      band_Si = json.load(file)

  if the same code is executed in the notebook below.