Add text from the to a content file

I want to be able to add a content of to some file in ‘contentdir’, so if README changes, the change will be rendered when Hugo runs next time.
I guess that it can be done with a shortcode, but I’ve looked through the documentation and discussions, and couldn’t find any hint on how to do that or if it is at all possible.

Currently, no.

But there are discussions and even pull requests related to this on Github.

Thanks, @bjornerik. Could you please point me to such discussion?

GitHub has a search engine. Please try that.