ZIP 209: add section heading for References.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

zip-0209.html

@@ -38,6 +38,9 @@ License: MIT</pre>
             <h2>Deployment</h2>
             <p>This consensus rule is not deployed as part of a network upgrade as defined in ZIP-200 <a href="#zip-0200" id="id5" class="footnote_reference">3</a> and there is no mechanism by which the network will synchronize to enforce this rule. Rather, all nodes should begin enforcing this consensus rule upon acceptance of this proposal.</p>
             <p>There is a risk that before all nodes on the network begin enforcing this consensus rule that block(s) will be produced that violate it, potentially leading to network fragmentation. This is considered sufficiently unlikely that the benefits of enforcing this consensus rule sooner are overwhelming.</p>
+        </section>
+        <section id="references">
+            <h2>References</h2>
             <table id="rfc2119" class="footnote">
                 <tbody>
                     <tr>

zip-0209.rst

@@ -55,6 +55,10 @@ This consensus rule is not deployed as part of a network upgrade as defined in Z
 
 There is a risk that before all nodes on the network begin enforcing this consensus rule that block(s) will be produced that violate it, potentially leading to network fragmentation. This is considered sufficiently unlikely that the benefits of enforcing this consensus rule sooner are overwhelming.
 
+
+References
+==========
+
 .. [#RFC2119] `Key words for use in RFCs to Indicate Requirement Levels <https://tools.ietf.org/html/rfc2119>`_
 .. [#protocol] `Zcash Protocol Specification, Version 2019.0-beta-37 [Overwinter+Sapling] <https://github.com/zcash/zips/blob/master/protocol/protocol.pdf>`_
 .. [#zip-0200] `ZIP 200: Network Upgrade Mechanism <https://github.com/zcash/zips/blob/master/zip-0200.rst>`_