Fix link to toolchains to work properly.
<p><code>List of <a href="../build-ref.html#labels">labels</a>; optional</code></p>
<p>
-The set of <a href="../toolchains.html">toolchains</a> this rule has access to.
+The set of
+<a href="../toolchains.html">toolchains</a>
+<a href="toolchains.html">toolchains</a>
+this rule has access to.
</p>
</p>Targets listed here are the set of toolchains whose <a href="${link make-variables}">Make
