Documentation updates: Explanation section rewrites and docstring updates

[jbrossman]

Depends on Sienna-Platform/InfrastructureSystems.jl#584

This pull request updates the documentation structure and navigation for PowerSystems.jl, improving organization, adding new topics, and aligning links with updated content locations. The changes focus on enhancing the developer and user experience by expanding references, reorganizing how-to guides, and updating documentation paths.

Documentation structure and navigation improvements:

• Added new supplemental attribute-related how-to guides and grouped them under a dedicated section in the navigation, making it easier to find information about attaching and querying supplemental data, grouping generators, modeling outages, and adding emissions or custom data.
• Reorganized and expanded the explanation section by adding new topics (such as three-winding transformers, grouping generators, hydro reservoir topology, emissions metadata, and outage data), and updated or moved several existing explanation pages for better clarity.
• Updated the reference section to use the reference/ directory instead of api/ for public API, glossary, type tree, and developer/internal documentation, reflecting a new documentation structure.
• Expanded docstrings throughout and added hyperlinking for navigation

Reference and fallback improvements:

• Expanded the ExternalFallbacks in docs/make.jl to include more InfrastructureSystems references, improving cross-linking and reducing documentation build errors for missing references.

Minor updates:

• Updated the contributor guidelines link in the pull request template to point to the new reference/developer_guidelines location.

No new functionality was introduced; these are documentation and reference-structure updates.

Related Issue

Closes #1504
Closes #1457
Closes #1448
Closes #1461

New Exports

HydroUnit is exported (oversight)

[codecov]

Codecov Report

❌ Patch coverage is 83.87097% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.15%. Comparing base (0650c45) to head (6e722c0).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/models/components.jl	33.33%	2 Missing ⚠️
src/models/cost_function_timeseries.jl	0.00%	1 Missing ⚠️
src/models/generation.jl	50.00%	1 Missing ⚠️
src/models/static_models.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1635      +/-   ##
==========================================
+ Coverage   84.13%   84.15%   +0.02%     
==========================================
  Files         204      204              
  Lines       10540    10536       -4     
==========================================
- Hits         8868     8867       -1     
+ Misses       1672     1669       -3     

Flag	Coverage Δ
unittests	84.15% <83.87%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/PowerSystems.jl	0.00% <ø> (ø)
src/base.jl	88.95% <100.00%> (+0.18%)	⬆️
src/definitions.jl	100.00% <ø> (ø)
src/get_components_interface.jl	80.00% <ø> (ø)
src/impedance_correction.jl	100.00% <ø> (ø)
src/models/HybridSystem.jl	75.64% <100.00%> (ø)
src/models/OuterControl.jl	64.70% <100.00%> (ø)
src/models/RoundRotorExponential.jl	86.66% <100.00%> (ø)
src/models/RoundRotorQuadratic.jl	86.66% <100.00%> (ø)
src/models/SalientPoleExponential.jl	64.28% <100.00%> (ø)
... and 24 more

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[kdayday]

@jbrossman I haven't taken a look yet, but FYI, about figures there's a different file path to get it to show up locally versus on github ("../" vs. "../../" or vice versa). We will want whichever one gets it to show up on the github Preview, so don't worry about it if it doesn't show up locally

[Copilot]

Pull request overview

Copilot reviewed 111 out of 169 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (4)

src/utils/print.jl:1

• The component_type argument type annotation is malformed Markdown/Documenter syntax (Type{<:Component}) and is likely to render incorrectly (or break doc builds). Prefer keeping the type expression as code (Type{<:Component}) and add the Component link outside the braces, e.g. 'Type to display (Type{<:Component}); see Component'.
  src/parsers/powerflowdata_data.jl:1
• The type annotation mixes backticks, braces, and @ref in a way that is hard to read and may render poorly. Consider simplifying the signature documentation to standard Julia syntax (e.g., Union{PowerFlowDataNetwork, String, IO}) and reference PowerFlowDataNetwork in the prose instead of embedding the link inside the type expression.
  src/models/branches.jl:1
• These docstrings state the endpoints are ACBus, but Branch can include DC branches (endpoints are DCBus) and potentially other branch-like components. To avoid misleading users, describe the endpoints as a generic bus/topology node (e.g., Bus) or explicitly document what endpoint types are supported for each branch subtype.
  docs/src/tutorials/manipulating_datasets.jl:1
• This inline link/code combination will render awkwardly ([ThermalFuels](@ref).NATURAL_GAS``). Prefer a single code span like ThermalFuels.NATURAL_GAS and (optionally) link `ThermalFuels` separately, e.g. 'updated to `ThermalFuels.NATURAL_GAS` (see `ThermalFuels`)'.