Improving tutorials

[jGaboardi]

Following up with #603 (the improved Quickstart tutorial) as an example all tutorials could use a bit more "story" in the future.

[slumnitz]

Tutorials are currently targeted towards advanced users of spaghetti and PySAL.
To improve on-boarding of and documentation for new users, or users not familiar with common spatial statistical workflows, tutorials will gradually be redesigned. Design principles that should be considered when rewriting tutorials include:

• showcasing and explaining the main functionalities of spaghetti, including relevant explanation
• a real data use case for each demonstrated functionality
• links to relevant papers or concepts spaghetti builds upon
• links to additional resources

Examples of good documentation are:

• https://docs.momepy.org/en/stable/user_guide/intro.html
• https://github.com/gboeing/osmnx-examples