docs: restore manual nav reorder (Concepts-first, grouped sections)

Re-applies the nav ordering from #188 that a force-push had reverted:
group Concepts into Evaluation strategies / Entity Mapping / Data
generation, and move Tutorials below Concepts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: omri374

mkdocs.yml

@@ -13,23 +13,24 @@ edit_uri: ""
 # the build script stages and converts them before Zensical runs.
 nav:
   - Home: index.md
-  - Tutorials (notebooks):
+  - Concepts:
+      - Evaluation strategies: 
+        - Home: evaluation.md
+        - Token evaluation: token_evaluation.md
+        - Span evaluation: span_evaluation.md
+        - Span matching strategies: span_matching_strategies.md
+      - Entity Mapping:
+        - Entity hierarchy: entity_hierarchy.md
+        - Why canonical entity mapping: why_canonical_entity_mapping.md
+        - Mapping scenarios: mapping_scenarios.md
+      - Data generation: data_generation.md
+  - Tutorials:
       - Generate data: notebooks/1_Generate_data.ipynb
       - PII dataset EDA: notebooks/2_PII_EDA.ipynb
       - Split by pattern: notebooks/3_Split_by_pattern_number.ipynb
       - Evaluate Presidio Analyzer: notebooks/4_Evaluate_Presidio_Analyzer.ipynb
       - Evaluate a custom Analyzer: notebooks/5_Evaluate_Custom_Presidio_Analyzer.ipynb
       - Interactive entity mapping: notebooks/6_Interactive_Entity_Mapping.ipynb
-  - Data generation: data_generation.md
-  - Concepts:
-      - Evaluation: evaluation.md
-      - Token evaluation: token_evaluation.md
-      - Span evaluation: span_evaluation.md
-      - Span matching strategies: span_matching_strategies.md
-      - Entity hierarchy: entity_hierarchy.md
-      - Why canonical entity mapping: why_canonical_entity_mapping.md
-      - Mapping scenarios: mapping_scenarios.md
-      - Migration guide: migration-guide.md
   - Presidio ↗: https://presidio.dataprivacystack.org
 
 theme: