docs: reorder Migration nav section logically

Group by flow: getting started  strategy/planning  specific topics
(by complexity: pages, controls, infrastructure)  tools & automation  reference.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: csharpfritz

mkdocs.yml

@@ -179,22 +179,22 @@ nav:
     - ViewState and PostBack Shim: UtilityFeatures/ViewStateAndPostBack.md
     - WebFormsPage: UtilityFeatures/WebFormsPage.md
   - Migration:
-      - Getting started: Migration/readme.md
-      - Known Fidelity Divergences: MigrationGuides/KnownFidelityDivergences.md
-      - Automated Migration Guide: Migration/AutomatedMigration.md
-      - Roslyn Analyzers: Migration/Analyzers.md
-      - Deprecation Guidance: Migration/DeprecationGuidance.md
+      - Getting Started: Migration/readme.md
       - Migration Strategies: Migration/Strategies.md
-      - Custom Controls: Migration/Custom-Controls.md
-      - Custom Control Base Classes: Migration/CustomControl-BaseClasses.md
-      - Deferred Controls: Migration/DeferredControls.md
+      - Migration Readiness Assessment: Migration/migration_readiness.md
       - Master Pages: Migration/MasterPages.md
       - User Controls: Migration/User-Controls.md
+      - Custom Controls: Migration/Custom-Controls.md
+      - Custom Control Base Classes: Migration/CustomControl-BaseClasses.md
       - FindControl Migration: Migration/FindControl-Migration.md
-      - .NET Standard to the Rescue: Migration/NET-Standard.md
+      - Deferred Controls: Migration/DeferredControls.md
       - Themes and Skins: Migration/ThemesAndSkins.md
       - Migrating .ashx Handlers: Migration/MigratingAshxHandlers.md
-      - Web Forms Application Migration Readiness: Migration/migration_readiness.md
+      - .NET Standard to the Rescue: Migration/NET-Standard.md
+      - Deprecation Guidance: Migration/DeprecationGuidance.md
+      - Automated Migration Guide: Migration/AutomatedMigration.md
+      - Roslyn Analyzers: Migration/Analyzers.md
+      - Known Fidelity Divergences: MigrationGuides/KnownFidelityDivergences.md
   - Migration Tests:
       - Overview: migration-tests/README.md
       - WingtipToys 2026-03-04: migration-tests/wingtiptoys-2026-03-04/report.md