tweak module 5

[alessandrofelder]

What is this PR
Here is how I addressed each point in the issue

slide 95: niksirbi made a really nice NIU+Python ecosystem graphic that would go well here.

I put it here.

slide 97: mention environments here and say we will cover them later?

Minor rewording to keep envs and installing packages contained to module 8. I've linked to module 8 (implementing "open in new tab" behaviour" here and tested manually, but don't understand the code my AI-assistant generated for this.

slide 98: we should cover the concept of an array before we introduce numpy functions here. And maybe not use class, but refer back to datatype/objects explanations from earlier

Had a go at implementing this.

slide 99: should values be a np.array or is the solver expected to convert? (arguably you could/should use existing list functions for this exercise if you have a list) Can we introduce instantiation of arrays from a list and with things likes np.ones/zeros(_like) first?

Moved randint slide from module 7 here. And added slide and exercise about np.zeros and np.ones.

slide 100: "A NumPy array is a class useful for mathematical operations on an entire collection." I would maybe remove this sentence?

I removed this sentence.

slide 102: The answer includes the word "vectorised" which has not been introduced.

I reworded this sentence.

References

Closes #11 . Tested by visual inspection of local deployment, and clicking on the new hyperlink.