Update documentation for music_utils.py to work with autodoc in sphinx

[coleslaw481]

refactor the documentation for music_utils.py to match docstring expected by autodoc and sphinx. Currently the documentation is just showing as raw text as one line as seen in this screenshot (run make docs to see in browser):

Note how the documentation is more readable for cellmaps_utils.cellmaps_utilscmd module and just plain text under cellmaps_utils.music_utils module