docs(tutorial): Clarify examples in chapter 5

[Nukesor]

While going through the tutorial, I found the description on the last example of chapter 5 very confusing.

As a beginner, at this point of the tutorial I had the mental model that a Parser always consumes/advdances the input.
Suddenly take is introduced without any further info, which uses checkpoints under the hood.

And to make this even more confusing, the output of the parse_list parser is changed to "accumulat[e] the results into a ()", which really doesn't make a lot of sense if you don't know that take doesn't care about the output of the contained parser due to the checkpoint logic.

There's really a lot of concepts to unwrap in this small piece of code and it took a bit of research to figure out why stuff worked the way it does.

I hope the new text is able to convey this knowledge in a better way.

[coveralls]

Pull Request Test Coverage Report for Build 11985707946

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 41.568%

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Totals
Change from base Build 11940029114:	0.0%
Covered Lines:	1299
Relevant Lines:	3125

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💛 - Coveralls

[epage]

Thank you for taking the time to fix this to help others in the future!