Added login instructions

interface/templates/registration/login.html

@@ -1,6 +1,11 @@
 {% extends "base.html" %}
 
 {% block content %}
+<div class="narrow">
+<p style="text-align: center">
+    Login is only required to administer a project.<br/>
+    If you have an ensemble code <a href="{% url 'register' %}">enter it here</a> instead.
+</p>
 <form method="POST" class="vertical">
     {% csrf_token %}
     {{ form }}
@@ -8,4 +13,5 @@
         <button type="submit">Login</button>
     </div>
 </form>
+</div>
 {% endblock %}