text: Title: Join documentation is out of date
  Body: **Describe the bug or question**
  As far as I can tell, the `join` [documentation](https://igorbenav.github.io/fastcrud/advanced/joins/) is out of date
  
  For example, it shows:
  
  ```python
  user_tier = await user_crud.get_joined(
      db=db,
      model=Tier,
      join_on=User.tier_id == Tier.id,
      join_type="left",
      join_prefix="tier_",,
      id=1
  )
  ```
  
  While the code suggests it should be `join_model` instead of `model`:
  
  https://github.com/igorbenav/fastcrud/blob/5e45aee16db9b541d98886472618ec967a3c527b/fastcrud/crud/fast_crud.py#L691
  
  