Add Esperanto to the list of languages

[rafael-nogueras]

I am opening this issue to explore whether @jbowens would be willing to accept a PR modifying the frontend/words.json file to add a new word list for a new language, Esperanto.

If so, please let me know, and I'll look into it. :-)

Also, I see all the words in other languages are all-uppercase. Beyond that, are there any restrictions / best-practices when creating a word list (beyond, I imagine, no profanity)?

[nochkin]

Each word should have multiple meanings, otherwise it would be hard to combine them.
Make sure you play many times with your friends to see how they work.