Add javadoc link to README.md and update some english translations

[er1c]

This isn't a great solution, but better than none.

I'm not sure if there is a great solution for i18n (internationalization) javadoc support, but this will help scratch my own itch when I'm browsing the -sources.jar artifacts.

[monkeyWie]

Wow, thank you very much, let's just keep English, don't consider for the i18n in code comment. I wrote some Chinese, because my English is not good🤣.