Design documentation and more comprehensive documentation for submodel and references with grandchildren aliases.

[TimWhiting]

This also adjusts the old keywords for submodel and reference in favor of the new, and adds an examples directory so that we can have samples to run to verify the correct output in the documentation.

[Copilot]

Pull request overview

Updates the mdBook guide to document “design” workflows and expands documentation around model imports (submodels/references) and aliasing, with supporting syntax-highlighting and runnable example sources.

Changes:

• Adds a new “Designs” chapter and reorders/renames guide chapters accordingly.
• Updates existing guide pages to use the newer import terminology/syntax and expands explanations/examples (including grandchildren/local aliasing).
• Adds a docs/guide/examples/10-designs/ directory with sample .on/.one inputs intended for documentation verification, and extends the Oneil highlight.js grammar.

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
docs/guide/theme/highlight.js	Updates Oneil syntax highlighting rules for new declarations and label parsing behavior.
docs/guide/src/SUMMARY.md	Adds the new “Designs” chapter and shifts Python-import docs to a new chapter number.
docs/guide/src/01-overview.md	Updates overview examples for model imports and adds a short designs intro/link.
docs/guide/src/09-importing-models.md	Expands and rewrites importing-models documentation and examples (references/submodels/local aliases).
docs/guide/src/10-designs.md	New comprehensive documentation page describing designs, application, and related behaviors.
docs/guide/src/11-importing-python.md	New/renumbered documentation page for Python imports, fallback behavior, and caching.
docs/guide/examples/10-designs/thruster.on	Example model used by designs documentation.
docs/guide/examples/10-designs/spacecraft.on	Example model used by designs documentation.
docs/guide/examples/10-designs/solar_system.on	Example model demonstrating nested submodels/aliases.
docs/guide/examples/10-designs/planet.on	Example base model for gravity designs.
docs/guide/examples/10-designs/multi_planet.on	Example showing multiple submodel instances with different designs.
docs/guide/examples/10-designs/moon_gravity.one	Example design file for moon-like parameters.
docs/guide/examples/10-designs/moon_design.one	Example design file targeting the moon model.
docs/guide/examples/10-designs/moon.on	Example moon model file.
docs/guide/examples/10-designs/mission_aug.on	Example showing design-driven augmentation reads.
docs/guide/examples/10-designs/mission.on	Example applying a design to a submodel instance.
docs/guide/examples/10-designs/mars_like.one	Example design overriding a nested aliased submodel parameter.
docs/guide/examples/10-designs/mars_gravity.one	Example design overriding planetary gravity parameters.
docs/guide/examples/10-designs/high_thrust.one	Example design overriding submodel-scoped parameters.
docs/guide/examples/10-designs/galaxy.on	Example demonstrating grandchildren/local alias reads.
docs/guide/examples/10-designs/derived_planet.one	Example design that both overrides and adds derived parameters.
docs/guide/examples/10-designs/cycle_test.on	Example model for cycle/error demonstration.
docs/guide/examples/10-designs/cycle.one	Example design intended to create a dependency cycle.

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[pixilcode]

The documentation looks good to me! Feel free to merge when ready.