Fix a regression in bookshelf properties

ram/portal/templates/bookshelf/book.html

@@ -115,7 +115,7 @@
                       </tr>
                     </tbody>
                   </table>
-                  {% if book_properties %}
+                  {% if properties %}
                   <table class="table table-striped">
                     <thead>
                       <tr>
@@ -123,7 +123,7 @@
                       </tr>
                     </thead>
                     <tbody class="table-group-divider">
-                    {% for p in book_properties %}
+                    {% for p in properties %}
                       <tr>
                         <th class="w-33" scope="row">{{ p.property }}</th>
                         <td>{{ p.value }}</td>