Hey all, we'd like to use this tool to generate TOCs in a bunch of .mdx files, though it seems like out-of-the-box it only supports .md and .markdown. How does adding .mdx to the list of valid markdown extensions sound? Or, alternatively, a way to pass in user-defined file extension(s) via some CLI flag? (--ext=mdx ?)

In the meantime, as a workaround, we've been using something like find . -name "*.mdx" | xargs doctoc ..., though it'd be nice to have it handled & supported via doctoc itself.

Thanks!