What happened to for-google-earth-developers.html

1. A concise explanation of the problem you're experiencing.

Cesium briefing and some web pages point to https://cesiumjs.org/for-google-earth-developers.html, but the page is "not found". Is it still available?

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

4. The Cesium version you're using, your operating system and browser.

It looks like the page was moved to