update README.md
update README.md

Added a line for javascript.jsx in the readme.
Popular vim plugins like vim-ployglot and vim-flow automatically set `javascript` filetypes to `javascript.jsx`
This took me a couple hours of frustration so I'd like to add this line in the README to help others out.
autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim,autozimu/LanguageClient-neovim