Add proposed spec for CRLs in news feed

i2p2www/pages/site/docs/spec/updates.html

 {% extends "global/layout.html" %}
 {% block title %}{% trans %}I2P Software Update Specification{% endtrans %}{% endblock %}
-{% block lastupdated %}{% trans %}May 2015{% endtrans %}{% endblock %}
-{% block accuratefor %}0.9.20{% endblock %}
+{% block lastupdated %}{% trans %}March 2016{% endtrans %}{% endblock %}
+{% block accuratefor %}0.9.25{% endblock %}
 {% block content %}
 <h3>{% trans %}Overview{% endtrans %}</h3>
 <p>{% trans -%}
@@ -481,6 +481,8 @@ The following &lt;feed&gt; elements are used:
 </li><li>
 &lt;i2p:release&gt; I2P update metadata. See below.
 </li><li>
+&lt;i2p:revocations&gt; Certificate revocations. See below.
+</li><li>
 &lt;updated&gt; Timestamp for the feed (conforming to
 <a href="http://tools.ietf.org/html/rfc4287">RFC 4287 (Atom) section 3.3</a> and
 <a href="http://tools.ietf.org/html/rfc3339">RFC 3339</a>. (required)
@@ -559,6 +561,34 @@ If a router is older than this, the user must (manually?) update to an intermedi
 
 
 
+<p><b>Atom &lt;i2p:revocations&gt; Details:</b></p>
+<p>
+This entity is optional and there is at most one &lt;i2p:revocations&gt; entity in the feed.
+This feature is scheduled for implementation in release 0.9.26.
+The specification below is preliminary and subject to change.
+</p><p>
+The &lt;i2p:revocations&gt; entity contains
+one or more &lt;i2p:crl&gt; entities.
+The &lt;i2p:crl&gt; entity
+contains the following attributes and content:
+</p>
+<ul><li>
+date (attribute): Timestamp for this entry (conforming to
+<a href="http://tools.ietf.org/html/rfc4287">RFC 4287 (Atom) section 3.3</a> and
+<a href="http://tools.ietf.org/html/rfc3339">RFC 3339</a>. (required)
+The date also may be in truncated format yyyy-mm-dd (without the 'T'); this is the "full-date" format in RFC 3339.
+In this format the time is assumed to be 00:00:00 UTC for any processing.
+</li><li>
+id (attribute): A unique id for the creator of this CRL.
+</li><li>
+The content of the entity is
+a standard base 64 encoded Certificate Revocation List (CRL) with newlines, starting with the line
+'<tt>-----BEGIN X509 CRL-----</tt>' and ending with the line '<tt>-----END X509 CRL-----</tt>'.
+See <a href="https://tools.ietf.org/html/rfc5280">RFC 5280</a> for more information on CRLs.
+</li></ul>
+
+
+
 <h3>{% trans %}Future Work{% endtrans %}</h3>
 <ul>
 <li>{% trans -%}