The code block looks gnarly in the table for some reason. Thinking about it, it may be better just to keep the documentation here to:

> Sets custom headers to be sent with each file to S3.
> **Default:** `{}`

And then after *Uploading your Static Assets* add another very short section: *Setting Custom HTTP Headers*, outlining how to use `S3_HEADERS` (along with relavant links — on that note can you use the `foo_` and `.. _foo http://bar.com` notation?)