Crash course update - Githubissues

What is the goal of this PR?

To improve the oboarding process for new users, via making the crash course clearer and more focused.

Crash course is now divided into "setup" and "pathways".
There are three pathways tailored to a user's previous experience: new users, relational users, and graph users.
Content in "new user" pathway is designed to start with database fundamentals and use conceptual modelling.
Content in "relational user" and "graph user" pathways are designed to use data structures and output formats that will be familiar, showing how to use them in TypeDB.
An unindexed page for a "document user" pathway has also been added.
All pathways user the same bookstore database as Academy as the data domain, with some modelling differences per pathway.

Do not edit the content of this comment. The PR reviewer should simply update this comment by ticking each review item below, as they get completed.

Trivial Change

Code

[ ] Packages, classes, and methods have a single domain of responsibility.
[ ] Packages, classes, and methods are grouped into cohesive and consistent domain model.
[ ] The code is canonical and the minimum required to achieve the goal.
[ ] Modules, libraries, and APIs are easy to use, robust (foolproof and not errorprone), and tested.
[ ] Logic and naming has clear narrative that communicates the accurate intent and responsibility of each module (e.g. method, class, etc.).
[ ] The code is algorithmically efficient and scalable for the whole application.

Architecture

[ ] Any required refactoring is completed, and the architecture does not introduce technical debt incidentally.
[ ] Any required build and release automations are updated and/or implemented.
[ ] Any new components follows a consistent style with respect to the pre-existing codebase.
[ ] The architecture intuitively reflects the application domain, and is easy to understand.
[ ] The architecture has a well-defined hierarchy of encapsulated components.
[ ] The architecture is extensible and scalable.