docs: revamp the how-to guides

[lostmygithubaccount]

From diataxis.fr:

How-to guides are directions that guide the reader through a problem or
towards a result. How-to guides are goal-oriented.

---

A how-to guide helps the user get something done, correctly and safely; it
guides the user’s action.

It’s concerned with work - navigating from one side to the other of a
real-world problem-field.

The current Ibis how-to guides are better than before, but lacking. This issue
lays out a proposed structure and articles for discussion/implementation over
the new few months. Opening for public feedback as well. If you have ideas, or
something's missing, please comment below!

I'll use bold for section headers and TODO lists for individual articles.

Configuration

• Interactive mode (including max rows/columns etc.)
• Default backend
• ...

Input and output

• Work with tables and views
• Work with CSV
• Work with Parquet
• Work with JSON
• Work with Delta Lake tables
• Work with cloud storage (possible 1 per AWS/Azure/GCP)
• ...

Analytics

• Selecting and dropping columns (link out to advanced selectors topic?)
• Filter
• Aggregate
• Group by
• Order
• Slice
• Case statements
• Add new columns (mutate)
• Join (merge tables)
• Cast to different datatypes
• Append data (union)
• Window functions
• Chaining expressions and the underscore API
• Work with numbers and booleans
• Work with strings
• Work with structs
• Work with arrays
• Work with selectors
• ...

Work with SQL

• Use existing SQL code
• Produce SQL code
• ...

User-defined functions (UDFs)

• Scalar built-in UDFs
• Scalar Python UDFs
• Scalar PyArrow UDFs
• Scalar pandas UDFs

Geospatial operations

• ...

Visualiztion

• altair
• graphViz
• matplotlib
• plotly
• plotnine
• seaborn
• streamlit
• ...

Extending

• ...