Add Ruby to Repo

[hoangvq288]

Which language are you adding? (If it's not widely known, or rather esoteric, can you provide a link to more information?)

Things to make sure of:

1. Did you create a new directory containing all the necessary files to run your hello world?
2. Does your addition have a readme with the same format as this example, including the language, instructions, and a screenshot of it running?