Fix all warnings in tutorials

[m3rlin45]

Summary:
This fixes all sphinx warnings found in our handwritten tutorial pages
Test Plan:
make clean-all
make html

then grepped the warnings to make sure none came from these files

generated docs:
https://837-143080897-gh.circle-artifacts.com/0/docs/index.html

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

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