core&ui: add discussion history (#450)

Co-authored-by: 无限UCW <45730483+wuxianucw@users.noreply.github.com>
Co-authored-by: undefined <i@undefined.moe>

packages/ui-default/templates/discussion_detail.html

@@ -34,6 +34,9 @@
         <li><a href="{{ url('discussion_edit', did=ddoc.docId) }}">
           <span class="icon icon-edit"></span> {{ _('Edit') }}
         </a></li>
+      {% endif %}
+      {% if ddoc.edited %}
+        <li data-discussion-history data-raw-url="{{ url('discussion_raw', did=ddoc.docId) }}">{{ _('Edited') }}</li>
       {% endif %}
         <li>{{ _('{0} views').format(ddoc.views) }}</li>
       {% if handler.user.hasPriv(PRIV.PRIV_USER_PROFILE) %}