Comment cleanups to improve generated docs

- added comments to fields which didn't have any.
- changed all `//` comments to the new format
- fixed indents/line lengths/style on lines I touched
The comment is pretty clear, it's just the usage that's not. ;) I think the question is, how much of the implementation details do you want to expose to the user here? If you added this description:

> This field typically means the maximum number of results per page, so if you wanted all of the results, you'd most likely have to use the page tokens to get multiple pages.

I think it'd be pretty clear. The current documentation seems to imply that you'll only get 10 variants back from the request; not 10 per page.