Create phrase book for xarray to/from iris

[ESadek-MO]

📚 Documentation

With the progress of #4994, perhaps a phrase book of sorts could be added to the documentation, to translate terminology between xarray, iris, and other similar libraries.
e.g. Iris might use non-lazy, whereas xarray uses eager.

[trexfeathers]

Cross reference:

• Iris ❤ Xarray docs page. #5025