Docs: User Guide Landing Page

[andrewendlinger]

Is your feature request related to a problem?

The User Guide landing page itself is currently not the most welcoming (unlike e.g. the Gallery):

Describe the solution you'd like

A small intro and a structured toctree could come a long way:

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Happy to turn this into a PR, but I thought I would discuss the toctree structure with you first.

Here is one option:

Data model

• Terminology
• Data Structures

Core operations

• Indexing
• Computation
• GroupBy
• Reshaping
• Combining

I/O & scaling

• I/O
• Dask

Visualization & pandas

• Plotting
• Pandas

Advanced features

• Duckarrays
• Hierarchical Data
• Options
• Testing

Domain‑specific workflows

• Time Series
• Weather & Climate
• Complex Numbers

Describe alternatives you've considered

Alternative

And one alternative:

Core Concepts

• Terminology
• Data Structures

Data Selection & Manipulation

• Indexing
• Reshaping
• Combining
• GroupBy

Computation & Performance

• Interpolation
• Computation
• Dask

Input/Output

• I/O

Visualization

• Plotting

Interoperability & Ecosystem

• Pandas
• Duckarrays

Specialized Applications

• Time Series
• Weather & Climate
• Complex Numbers

Advanced Topics & Configuration

• Hierarchical Data
• Options
• Testing

Additional context

(Already added 'Complex Numbers' as a section, in case #10235 gets merged.)

[scottyhq]

While doing a bit of documentation review today with @benbovy and @keewis , we're thinking of cleaning up the 'Data Structures' section, another change that would be nice is move up the classic 'data model schematic' figure to the top of the page, as currently it's a bit buried! Could also put it in the repo readme:

https://docs.xarray.dev/en/latest/user-guide/data-structures.html#dataset