Migrate to jupyter-book for rendering

[datadavev]

Jupyter-book is a markdown based documentation environment that plays well with github markdown and offers many extended capabilities that may be leveraged by Science-on-schema.org:

• Automated contents, cross reference, index, glossary, etc management
• Inclusion of files outside of the markdown means examples and docs can share the same sources
• Ability to include executable segments such as jupyter notebooks or portions thereof
• Integrated with GH actions for automated build and publish
• Many layout and formatting options

As a proof of concept the feature-jupyterbook branch in my fork uses plain markdown copied into a jupyterbook folder that is rendered on push using a GH Action.

In that POC, the Getting-Started guide was modified to use the jupyter-book markdown, while Dataset and DataRepository are untouched.

My impression is that this format could be used almost immediately, with progressive refinement as appropriate.

[datadavev]

Suggesting this for release 1.3 primarily to support inclusion of practical, executable examples within the guidelines.