Add language pack for MDX

[trevordmiller]

MDX is a new language that combines Markdown and JSX. It's becoming very popular in the JavaScript + React community lately. Per the discussion in mdx-js/mdx#119, vim-mdx-js is going to be the main MDX language pack for Vim. Could it be added to vim-polyglot for .mdx files?

cc: @jxnblk

[trevordmiller]

Although for this to be in vim-polyglot, @jxnblk should probably remove https://github.com/jxnblk/vim-mdx-js/blob/4bf61b0728a387a241b48691f5b5adf0b03e1ea2/ftdetect/mdx.vim#L8, so only .mdx files are detected as markdown.mdx filetype.

[sheerun]

For now I've overwritten ftdetect part

[trevordmiller]

Awesome! I’m looking forward to this being released. cc @jxnblk

[sheerun]

This is released, just update your plugins

[trevordmiller]

@sheerun I removed vim-mdx-js from my plugins, upgraded my vim-polyglot plugin, restarted Vim, and now .mdx files are not being recognized correctly. :set filetype? in an .mdx file shows filetype=conf.

[sheerun]

Yes I did something stupid, but it should work now. Also upstream accepted my PR with fixed ftdetect vim-polyglot uses this plugin unmodified

[trevordmiller]

Works great! Thanks :)