Add more `info_comparison` units

[yunruse]

Off the back of

• 17

it would be nice to extract out a little YAML list of "comparison" units — using the exact same Catalogue format — for comparison.

Some sources could include (taken from https://en.wikipedia.org/wiki/Category:Lists_by_size):

• [ ] https://en.wikipedia.org/wiki/List_of_largest_cities
• [ ] https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area
• [ ] https://en.wikipedia.org/wiki/Continent#Area_and_population
• [ ] https://en.wikipedia.org/wiki/List_of_Solar_System_extremes

[yunruse]

It would also help to extract out noether/catalogue/info to just noether/info; it's a strange place for that to be