[DOC] $userId was not defined in demo jupyter notebook product_recommendation_demo.ipynb

[zliang9]

Willingness to contribute

Yes. I would be willing to contribute to this for with guidance from the Feathr community.

URL(s) with the issue

In demo jupyter notebook product_recommendation_demo.ipynb in the link below:

https://github.com/feathr-ai/feathr/blob/9a98253481c6001a6a4c52b45dcd5a6eb35be391/docs/samples/azure_synapse/product_recommendation_demo.ipynb

Variable "$userId" was used in section "3. Prerequisite: Set the required permissions", however it was not defined in the code above, and not obtainable in cloud shell either.

Likely it should be "$objectId" instead.

Description of proposal (what needs changing)

Substitute "$userId" with "$objectId" instead, in section "3. Prerequisite: Set the required permissions", on this page https://github.com/feathr-ai/feathr/blob/9a98253481c6001a6a4c52b45dcd5a6eb35be391/docs/samples/azure_synapse/product_recommendation_demo.ipynb