Before, we tested the examples/ directory using "ExampleXX", but this is
not ideal because it literally embeds the call to `main` into example
godoc output. This stops doing that for a different infrastructure.
This also makes sure there's a godoc example for both the main package
and wasi, so that people looking at https://pkg.go.dev see something and
also a link to our real examples directory.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
