notebooks: clean up tags

[reshamas]

Notebook title: various
Notebook url: various

Issue description

Some tags can be streamlined to reduce the number of categories. There are currently ~80 categories.

Tags:
https://www.pymc.io/projects/examples/en/latest/blog/tag.html

Examples

1. "Aesara" and "aesara"
2. "BART" and "Bayesian additive regression trees"
3. "Bayesian workflow" and "bayesian workflow"
4. "truncated" and "truncation"
5. "gaussian processes" and "gaussian process"
6. "generalized linear models" and "generalized linear model" notebook: model_selection; update tag #430
7. "censored" and "censoring"
8. "hierarchical" and "hierarchical model"
9. "prediction" and "predictions"
10. etc

[reshamas]

@drbenvincent Did we miss this one, or is my website cached?
"gaussian processes" and "gaussian process"