fixes to documentation

[jd-lara]

Changes from Fable review of #1635.

Correctness fixes (would mislead users or error if run)

• how_to/convert_transformer_impedance.md: the example transformer's rating was set as 0.5 labeled "SYSTEM_BASE p.u." — rating is stored on the device base, so the example silently encoded 25 MVA instead of 50 MVA. Now rating = 1.0 on the device base.
• how_to/use_context_managers.md: the begin_supplemental_attributes_update example constructed FixedForcedOutage(; mean_time_to_recovery, mean_time_to_failure) — neither field exists on that struct. Replaced with a valid GeometricDistributionForcedOutage example.
• how_to/link_hydro_reservoirs_to_turbines.md: example 2 rebuilt sys/bus from scratch but then linked the reservoir from the discarded first system. The page now uses one System throughout.

Math / semantics precision

• per_unit.md + convert_transformer_impedance.md: getters apply only the MVA-ratio part of the base conversion; added an explicit warning that the voltage-ratio correction is assumed to be 1 (rated voltage = bus base voltage) and must otherwise be applied manually.
• three_winding_transformers.md: $Z_{12}, Z_{23}, Z_{13}$ are the pairwise (delta) leakage impedances, not the star impedances; corrected PSS/E field semantics (CZ/CW/CM flags, WINDV/NOMV/ANG/SBASE1-2 field names verified against the PTI parser).
• Docstring fixes where the text contradicted the code directly beneath it:
  • get_component(sys, uuid) / get_available_component(sys, uuid) throw ArgumentError on a missing UUID (they do not return nothing)
  • add_subsystem! throws IS.InvalidValue when subsystems would exceed the bus count
  • Storage's only concrete subtype is EnergyReservoirStorage (HybridSystem is a StaticInjectionSubsystem)
  • get_services errors (not "returns empty") for devices that don't support services
  • All three outage struct docstring signatures now include the monitored_components field
  • calculate_IM_torque_params: A is the quadratic and B the linear torque-speed term (C = 1 − A − B is the constant)
  • rating_b/rating_c are second/third ratings (RATE_B/RATE_C), not winding sides
  • get_from_bus/get_to_bus return Bus (DC branches have DCBus endpoints)
  • Service subtype list now includes ConstantReserveGroup; ImportExportCost weekly_limits → weekly_limit typos; backtick/apostrophe typos in cost_function_timeseries.jl
  • get_associated_supplemental_attributes docstring signature and example matched to the actual function
• Glossary: filled the empty DERA1 entry, fixed the doubled REPCA1 label, and corrected the claim that ExponentialLoad is a ZIP model.
• buses_type_explanation.md: removed a garbled duplicated sentence and fixed Ref: → REF.

Verbosity reduction (~190 net lines)

• use_context_managers.md: removed duplicated/incorrect supplemental-attribute examples (now links to the dedicated how-to), the near-clone time-series example, and the redundant "Best Practices" section.
• Deleted orphaned explanation/transformer_per_unit_models.md (content verbatim in per_unit.md and the page was dropped from nav); retargeted the two @ref transformers_pu links to transformers_pu_per_unit.
• power_concepts.md: collapsed the triple statement of units/getters into the summary table.
• supplemental_attributes.md: merged the "Benefits" and "Compared to other approaches" sections into the motivation paragraph.
• add_supplemental_attributes.md: merged the near-identical bulk and shared-attribute examples.
• time_series.md: the "Multiple Forecast Intervals" code blocks duplicated the tutorial call-for-call; kept the concept, linked the tutorial.
• working_with_time_series.jl: trimmed the re-inspection tail that re-printed components and re-explained an earlier point.
• manipulating_datasets.jl: dot-access warning now links to @ref dot_access instead of duplicating system.md (and drops the hardcoded stable URL).
• dynamic_data.md: deduplicated the static/dynamic two-layer explanation.

Verification

• julia --project=test test/runtests.jl: 11735/11735 pass
• Formatter run clean
• Docs build: all errors are pre-existing/environmental — failed InterLinks inventory download in the sandbox plus the known dependency on Flesh out 1-line docstrings for key types InfrastructureSystems.jl#584 (ComponentContainer, InfrastructureSystemsComponent, InfrastructureSystemsInternal fallbacks). No errors from files changed here; all modified @example blocks execute.

Not addressed (pre-existing, out of scope for a docs PR)

• The power_system_structs.json descriptor comments for Transformer2W r/x/rating still say "pu (SYSTEM_BASE)" while runtime behavior (and the new docs) are device base — needs a descriptor + regeneration pass.
• HybridSystem.jl setters set_electric_load!/set_storage!/set_renewable_unit!/set_interconnection_efficiency! reference an undefined variable and would UndefVarError if called — behavioral bug, should be a separate issue/PR.

🤖 Generated with Claude Code

[kdayday]

@jd-lara I leave this to you to verify correctness on this point

[kdayday]

Left one question for you on rework of the starbus page, otherwise looks good to me