Document some more items like renderScene

[afkcodes]

Hey @grahammendick , I was actually going through the medley app and i found that renderScene is use there but there is no documentation for the same. Can we slowly start documenting those.

And what does the renderScene do. and in which cases we should use this.

[grahammendick]

Hey, before I added a component api a couple of years ago renderScene was the only way to use the Navigation router. But now there’s a component api, I don’t advertise the renderScene approach anymore.

I added the component api in a non-breaking way, so the renderScene still works exactly the same and there was no need to update the samples. It's useful to keep a sample using renderScene so that inquisitive people can find out about it without cluttering up the documentation.