How to run the basic example with only dune, no docker

Hi @anmonteiro

Do you have an idea as to why I receive this error from my basic lambda? I've changed the `build.sh` to build with only dune without docker. Although it's likely my build script is incorrect now and is the root issue of this, the basic example doesn't work as-is because it lacks the `esy.json` and `esy.lock` file that the dockerfile expects.
```
{
"errorMessage": "RequestId: 5489ab76-43af-4303-9ec8-9984e5ae7c44 Error: fork/exec /var/task/bootstrap: exec format error",
"errorType": "Runtime.InvalidEntrypoint"
}
```

```
#!/usr/bin/env sh

set -eo pipefail

root_path=$PWD

# Start in examples/basic/ even if run from root directory
cd "$(dirname "$0")"

rm -rf bootstrap
# possible that this is the issue because i left out --profile=static
dune build basic.exe
mv ../../_build/default/examples/basic/basic.exe ./bootstrap
zip -j ./ocaml.zip bootstrap

cd $root_path
```