docs: update tutorial according to review

[IronCore864]

Minor changes to the tutorial according to Anne's suggestion.

Closes #464.

This PR makes sure:

• It starts with a clear description of what the learner can expect to achieve from the tutorial
• The language of the tutorial assures the user that the instructor is on the same journey (“we”, not just “you”)
• The tutorial is reproducible with a mock setup which can easily be duplicated for the target user (a mock HTTP server instead of unknown services)
• It focuses on a single installation method and does not provide alternatives to users
• Tutorial is broken down into multiple smaller, logical steps and (where necessary) guides the user to observe the expected outcome at each step
• The amount of explanation is minimal and generally limited to necessary topics for the learner; links are used to connect the user to further reading on related topics
• Listing Python as a prerequisite to spell out early on so that users don't fail halfway through the tutorial because they can't run http.serve

[benhoyt]

Looks good. One minor comment.