isPreview documentation is broken

[npdoty]

Description of problem

What happened?:

https://respec.org/docs/#isPreview

Current docs say to use is Preview inside var respecify. This is invalid JavaScript, and Respec does not render.

Also, even with isPreview and inside the standard configuration object, I don't get the annoying warning to show up. And the documentation isn't clear that this is for Pull Request previews, which need additional values, and isn't just for an annoying red warning box like for an out of date or deprecated document.

Expected behavior:

Docs should describe valid JavaScript text so that Respec doesn't break, and so that the annoying red warning box is displayed with the relevant info.