Improve translation in HOAS tutorial

[patrick-nicodemus]

The HOAS tutorial refers to "commodity" features at several points.
This seems like a translation of the French term "commodité"; this dictionary suggests translating it as "convenience" and this is more readable to me.
I would suggest replacing "commodity" with "convenience" everywhere in the tutorial.

(For me, "commodity" carries the connotation in economics of a good that is easy to buy and sell in large volumes, such as oil, gas, wheat, nickel)