Reword explanation of model binding in a context

[jbn]

In Chapter 2, the markdown prior to In [4] says, "[t]o reset the model [...]". I initially read this as though there was some sort of weird introspection going on where the pymc3.model.Model object bound to model dropped its variables; then, it added the new ones. I didn't read the underlying code, but that seems unlikely -- it's just seems like a new binding. (The object IDs of model before and after supports this.) Unless I am incorrect, this bit of text may confuse people.

P.S. Thanks for doing this! Since I read @CamDavidsonPilon's book already, this is a great map to learn PyMC3.

[mmargenot]

That's a very good point! I will probably change the wording a bit on your first edit, the "To create a new model" one, to "To use the same name for a different model" since that was more what I was going for.

Good catch on the confusing wording.

[mmargenot]

I'm glad that you like it!