fix typos, make pedantic grammar tweaks, and modify wording

[JackElsey]

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[jtwhite79]

Thanks @JackElsey . We might hold off on merging this pr until after the upcoming course just to make sure everyone has a consistent notebook version...

[JackElsey]

OK, I'll hold off on making more commits until I've worked through more of the tutorials then.

[JackElsey]

There are a couple probable equation typos that you may want to be aware of:

First, I don't think the variogram formula here should have $h$ in the denominator.

$$\hat{\gamma}\left(h\right)=\frac{1}{2\left(h\right)}\left(z\left(x_1\right)-z\left(x_2\right)\right)^2$$

Second, the Baye's theorem equation here has an unnecessary > in the numerator.

$$P\left(\boldsymbol{\theta}|\textbf{d}\right)=\frac{P\left(\textbf{d}|\boldsymbol{\theta}\right) P\left> (\boldsymbol{\theta}\right)}{P\left(\textbf{d}\right)}$$

[briochh]

Hey @JackElsey, I have switched this PR over to the develop branch, so we can continue to field contributions without disrupting the main branch till after the course. Feel free to keep pushing to it.