Add `expand` to table of contents
<a href="/collapse">collapse</a><br>
<a href="/convert">convert</a><br>
<a href="/diff">diff</a><br>
+ <a href="/expand">expand</a><br>
<a href="/explain">explain</a><br>
<a href="/export">export</a><br>
<a href="/export-prefixes">export-prefixes</a><br>
