pyMC4 Design Guide Changes Review

Hi,
I’m trying learn pyMC4 by porting examples from McElreath’s Statistical Rethinking Course’19.

I know intermediate pyMC3 so, in the process of transition, I modified some parts of the pyMC4 guide to give it a beginner friendly touch (especially the coroutines).
Here is the document.
I plan to create a PR to suggest these changes to the core-devs.

Please give some suggestions for improvement and changes.