Missing English translation

[fire]

https://github.com/RVC-Project/Retrieval-based-Voice-Conversion-WebUI/blob/main/docs/README.en.md

Update the English readme?

1. What does https://github.com/RVC-Project/Retrieval-based-Voice-Conversion-WebUI do?
2. How can I use an existing model?
3. How can I train a new model?
4. How long does it take?
5. What known problems and issues are there?

[fumiama]

Well, all languages version now is incomplete. Need to expand it.