docs(wasm-languages): ruby updates

[vdice]

Sample setup/code/manifest updates similar to #1403

Bonus: I did see the following error in the app logs when pinging the endpoint. Cause for alarm? Fixable? (Response was still a 200 and contained the expected "Hello, Fermyon" body)

$ spin up
Logging component stdio to ".spin/logs/"

Serving http://127.0.0.1:3000
Available Routes:
  ruby: http://127.0.0.1:3000
2024-10-30T22:37:06.498213Z ERROR spin_http::wagi: Invalid header name error=invalid HTTP header name header_name=ruby 3.4.0dev (2024-06-28T17

[itowlson]

Could you raise an issue on Spin for the header error please? It seems like it's just a quirk, but at least then we'll have a reminder to check it out. Thanks!

[github-actions]

🚀 preview deployed successfully to Fermyon Cloud and available at https://fermyon-developer-pr-1406-aipqt4ku.fermyon.app