ToDo: add sonification of ApRES data

[jkingslake]

add a page about sonification of the ApRES data.

Follow this guide: https://gist.github.com/akey7/94ff0b4a4caf70b98f0135c1cd79aff3

[jkingslake]

this capability will soon be included in a working form in XApRES (see here for a working code in a feature branch: https://github.com/ldeo-glaciology/xapres_package/blob/8f25013a0e61fdb72d6b14bef2f2ecf764eb0883/xapres_package/utils.py#L154), so it should be easy to include in the textbook page.

[jkingslake]

this is now a feature of XApRES:

ds.chirp.isel(time=300, chirp_num=0, attenuator_setting_pair=0).sonify()