[DOCS] Reorganize the Documentation

[christophercrouzet]

Category

• [ ] Report an error in the documentation.
• [ ] Request for something to be documented.
• [x] Suggestion to improve the documentation.
• [ ] Other (please explain)

Description

• Change the Python reference page to strictly be a listing of the API, and move the remaining content into a dedicated user guide page, aligning it with our existing notebooks.
• Rename the “Built-Ins Reference” page to “Language Reference”.
• Ensure both reference pages have a clear table of contents on their landing pages that lists and groups all API components in a compact format. The detailed content should be stored on separate pages dedicated to each group (e.g.: Arrays, Streams, Graphs, Spatial Math, Time Primitives, Geometry, ...).
• Remove the simulation reference section as it's being moved to Newton, and rename the “Core Reference” page to “API Reference”.

Use Newton's documentation as a reference.

[shi-eric]

I guess you should create several sub-issues. At least the task about removing the simulation reference can't be done until November.