Fix docs generator skipping index.json in providers/

providers/index.json has a different shape from recipe files; the docs
generator now skips it when loading providers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: m2de

docs/generate.py

@@ -107,6 +107,8 @@ def load_providers() -> list[dict]:
     """Load all provider JSON files, sorted by display_name."""
     providers = []
     for path in sorted(PROVIDERS_DIR.glob("*.json")):
+        if path.name == "index.json":
+            continue
         with open(path) as f:
             data = json.load(f)
         providers.append(data)