docs: fix usage of user's groups

docs/expressions/reference/user-object.md

@@ -2,20 +2,25 @@
 
 The User object has the following attributes:
 
- - `username`: User's username.
- - `email` User's email.
- - `name` User's display mame.
- - `is_staff` Boolean field if user is staff.
- - `is_active` Boolean field if user is active.
- - `date_joined` Date user joined/was created.
- - `password_change_date` Date password was last changed.
- - `attributes` Dynamic attributes.
+- `username`: User's username.
+- `email` User's email.
+- `name` User's display name.
+- `is_staff` Boolean field if user is staff.
+- `is_active` Boolean field if user is active.
+- `date_joined` Date user joined/was created.
+- `password_change_date` Date password was last changed.
+- `attributes` Dynamic attributes.
+- `pb_groups` This is a queryset of all the user's groups.
+
+    You can do additional filtering like `user.pb_groups.filter(name__startswith='test')`, see [here](https://docs.djangoproject.com/en/3.1/ref/models/querysets/#id4)
+
+    To get the name of all groups, you can do `[group.name for group in user.pb_groups.all()]`
 
 ## Examples
 
 List all the User's group names:
 
 ```python
-for group in user.groups.all():
+for group in user.pb_groups.all():
     yield group.name
 ```