Stop referring back to factory methods for information

[rtoy]

Describe the issue
See, for example, https://webaudio.github.io/web-audio-api/#dom-iirfilteroptions-feedforward

See feedforward argument of createIIRFilter() for other constraints.

I think the preferred way of creating nodes and such is through the constructors. It's annoying to have to refer back to the factory method for constraints and other items. I think it would be really nice to have the factory methods refer back to the corresponding constructors to describe how the factory method works instead of the other way around.

Perhaps we would end up saying c.createFoo(args) is basically the same as new FooNode(c, args) which makes it really simple and clear on what the factory method does and all the relevant details will be in the constructor.