Minor rewording. Added tip about meaning of compound var and expanded

the example code to contain `else` statements.

Author: mtrojanowski

cookbook/form/form_customization.rst

@@ -794,7 +794,13 @@ field) are rendered separately, usually at the top of your form:
         <?php echo $view['form']->render($form); ?>
 
 To customize *only* the markup used for these errors, follow the same directions
-as above, but now check if the ``compound`` attribute is set to ``true``:
+as above, but now check if the ``compound`` variable is set to ``true``. 
+
+.. tip::
+
+    If the ``compound`` variable is ``true``, it means that what's being 
+    currently rendered is a collection of fields (e.g. a whole form), and not 
+    just an individual field.
 
 .. configuration-block::
 
@@ -810,6 +816,8 @@ as above, but now check if the ``compound`` attribute is set to ``true``:
                                 <li>{{ error.message }}</li>
                             {% endfor %}
                         </ul>
+                    {% else %}
+                        {# display the errors for a single field #}
                     {% endif %}
                 {% endif %}
             {% endspaceless %}
@@ -825,6 +833,8 @@ as above, but now check if the ``compound`` attribute is set to ``true``:
                         <li><?php echo $error->getMessage() ?></li>
                     <?php endforeach; ?>
                 </ul>
+            <?php else: ?>
+                <?php // render the errors for a single field ?>
             <?php endif; ?>
         <?php endif ?>