Improve legend to depth

The legend currently says

Depth “0” means visiting no children pages (only entry points).

followed by the section where one selects assets for preloading.

It can be improved by pointing out that depth ‘0’ also effectively disables assets preloading, eg

Depth “0” means visiting no children pages or assets (only entry points).

Better still would be to grey out the assets preloading section on refresh if ‘0’ is entered.