Hi!

The upstream MultiMarkdown spec
<https://rawgit.com/fletcher/human-markdown-reference/master/index.html>
specifies cross-references such as the following:

,--- cross.mmd
# Overview [MultiMarkdownOverview]

Point to [Section][].

# Section

Point to [MultiMarkdownOverview][].
`---

which are not currently supported by this package:

,---
$ multimarkdown cross.mmd
<h1 id="overviewmultimarkdownoverview">Overview [MultiMarkdownOverview]</h1>

<p>Point to <a href="#section" title="Section">Section</a>.</p>

<h1 id="section">Section</h1>

<p>Point to [MultiMarkdownOverview][].</p>
`---

Thanks,
Guillem