Update tutorial 1 colab

[M-Salti]

The parameter names passed to write_documents_to_db and TfidfRetriever in the Colab notebook of Tutorial 1 need to be updated from datastore=datastore to document_store=document_store, because they currently produce TypeError.

The variable datastore = SQLDocumentStore(url="sqlite:https:///qa.db") should also be updated to document_store = SQLDocumentStore(url="sqlite:https:///qa.db") for naming consistency

[tholor]

Oh yes, totally! Thanks for reporting. Do you want to create a PR or should I take care of this?

[M-Salti]

I think it would be better if you update it. Just to keep the notebook on your drive, I guess

[tholor]

Fixed :)