docs: add documentation index

docs/README.md

@@ -0,0 +1,20 @@
+# Documentation
+
+## Philosophy
+
+- [Design Philosophy](philosophy.md) - Core principles and Coherence Loop
+- [Fieldnote Template](fieldnote-template.md) - Frontmatter schema
+
+## Tools
+
+- [Coherence Tools](../tools/coherence/README.md) - Site validation tools
+
+## Quick Start
+
+```bash
+# Run all coherence checks
+python3 tools/coherence/run-coherence.py
+
+# Fix issues
+python3 tools/coherence/fix-frontmatter.py public/fieldnotes/
+```