This will allow folks to drop a GLB into the following page to get a
WebGL preview. It always uses the latest version of Filament via unpkg.
https://google.github.io/filament/viewer
After the next release we can also use the `<filament-viewer>` component
itself from unpkg and remove the local copy.
This is a simple place to host WebGL demos and tutorials, we can prettify later. It will show up at:
https://google.github.io/filament/
The hugo config specifies the output holder to be ../docs which is where our GitHub Pages site is located.
Note that this commit adds the *source* to the site, it does not publish the actual site. When we're ready to publish the actual site, we'll do:
```terminal
cd site ; hugo ; cd ..
git add docs ; git commit
```
