Address some typos in the SDK Hero Tutorial Notebook

[thomasp-ms]

PR into Azure/azureml-examples

Checklist

I have:

• [x] read and followed the contributing guidelines
• [x] checked everything in the notebook, up to (and NOT including) the "Deploy the model from registry to the online endpoint" section.

Changes

• various path fixes
• path -> source in the load_component() function call