Miscellaneous tutorial updates and fixes

[likethesky]

Motivation

Ensure logging is not annoying, add comments to guide users of tutorials, fix a couple typos.

Changes proposed

• remove VerboseLevel.OFF in: Hierarchical_modeling, Hierarchical_regression, Item_Response_Theory, & Zero_inflated_count_data
• add comments setting expectations to users that the following tutorials could take a number of minutes, or possibly many minutes to an hour or more: Hierarchical_modeling, Hierarchical_regression, Item_Response_Theory, Sparse_Logistic_Regression, & Zero_inflated_count_data
• fix typo: possesion to possession in Item_Response_Theory
• fix typo: remove extra cell at end of Bayesian_Logistic_Regression

Test Plan

Use Colab to ensure all changes work correctly.

Types of changes

• [x] 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

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [x] The title of my pull request is a short description of the requested changes.