Refined the template used by the person-link template tag to do better for document authors without an email address.

- Legacy-Id: 18613

ietf/templates/person/person_link.html

@@ -1,7 +1,15 @@
 {# Copyright The IETF Trust 2020, All Rights Reserved #}{% spaceless %}
+{% if email %}
 <a {% if title %}title="{{ title }}"{% endif %} href="{% url 'ietf.person.views.profile' email_or_name=email %}">
   <span class="{{class}}">{{ plain_name }}</span>
 </a>&nbsp;<a href="mailto:{{ email|urlencode }}">
   <span class="fa fa-envelope-o tiny"></span>
 </a>
+{% elif name %}
+<a {% if title %}title="{{ title }}"{% endif %} href="{% url 'ietf.person.views.profile' email_or_name=name %}">
+  <span class="{{class}}">{{ plain_name }}</span>
+</a>
+{% else %}
+  <span class="{{class}}">{{ plain_name }}</span>
+{% endif %}
 {% endspaceless %}