better status code returns

I mention in the README that there was a limitation from Lambda of returning 200. I don't think this is true.

https://github.com/eebbesen/sheet_zoukas-lambda?tab=readme-ov-file#notes

See the default lambda example:
```ruby
require 'json'

def lambda_handler(event:, context:)
# TODO implement
{ statusCode: 200, body: JSON.generate('Hello from Lambda!') }
end
```