text: Title: Pycharm don't like `instance(docs, DocumentArray[MyDoc])`
  Body: # Context
  
  this code run 
  
  ```python
  from docarray import BaseDocument, DocumentArray
  
  
  class MyDoc(BaseDocument):
      name: str
  
  
  docs = DocumentArray[MyDoc]([MyDoc(name='hello') for i in range(4)])
  
  assert isinstance(docs, DocumentArray[MyDoc])
  ```
  
  but Pycharm doesn't like it 
  
  ![Image](https://user-images.githubusercontent.com/55492238/221812688-b3b85059-7a1b-4286-92fb-12152bf65da3.png)
  
  
  Probably because it does not detect that `DocumentArray[MyDoc]` is just a normal class