Update autocompletion documentation

docs/autocomplete.rst

@@ -7,7 +7,9 @@ available options is rather big. In this case Django JET allows you to load thes
 
 In order to achieve this functionality all you have to do is:
 
-* Specify which model fields should be searchable by AJAX queries. Add this static method to all models which you want to be searchable with AJAX:
+-
+    Specify which model fields should be searchable by AJAX queries. Add this static method which must return
+    a ``tuple`` or ``list`` of fields you want to be searchable with AJAX:
 
 .. code:: python
 
@@ -15,6 +17,12 @@ In order to achieve this functionality all you have to do is:
     def autocomplete_search_fields():
         return 'field1', 'field2'
 
+    # for single field
+
+    @staticmethod
+    def autocomplete_search_fields():
+        return 'field1',
+
 Example from Django JET demo site:
 
 .. code:: python
@@ -36,7 +44,7 @@ Example from Django JET demo site:
         def autocomplete_search_fields():
             return 'name', 'city__name'
 
-* Use custom AJAX filter class ``jet.filters.RelatedFieldAjaxListFilter`` if you have any foreign key list filters:
+- Use custom AJAX filter class ``jet.filters.RelatedFieldAjaxListFilter`` if you have any foreign key list filters:
 
 .. code:: python
 
@@ -48,7 +56,7 @@ Example from Django JET demo site:
             ('address', RelatedFieldAjaxListFilter),
         )
 
-* Now all your admin select boxes will perform AJAX queries to load available options while you type.
+- Now all your admin select boxes will perform AJAX queries to load available options while you type.
 
 .. note::
     This work for both ForeignKey and ManyToManyField fields.