Add missing AutocompleteFields to Person model search_fields

as per https://github.com/wagtail/wagtail/pull/10341#issuecomment-1512846879

bakerydemo/base/models.py

@@ -79,6 +79,8 @@ class Person(
     search_fields = [
         index.SearchField("first_name"),
         index.SearchField("last_name"),
+        index.AutocompleteField("first_name"),
+        index.AutocompleteField("last_name"),
     ]
 
     @property