Add logistic growth tutorial

[martinjankowiak]

open in colab

[martinjankowiak]

our notebooks assume that pyro is installed which is not the case for colab. do we just make a second copy of the notebook that has the pip install at the top?

[martinjankowiak]

• typo: +to => "Next let's extract sublineages corresponding two of the"
• arguably rate_scale isn't doing much in the last model since there are only two lineages
• typo: generalization section => "usepyro.plate"

generally looks great and i think this will be a good fit for the workshop

[fritzo]

Thanks for making this @martinjankowiak!

[martinjankowiak]

thank for your substantial improvements!