some structure

docs/index.md

@@ -3,13 +3,13 @@
 SuperCon 2 is the staging-area of [SuperCon](http://supercon.nims.go.jp), the 'de-facto standard' database of superconductors materials.
 SuperCon 2, collect experimental data automatically extracted from scientific documents and provide a workflow to correct them efficiently and with high quality.
 
-- [User interface](curation_interface.md)
-- [Curation workflow](curation_workflow.md)
-- [Curation guidelines](guidelines/readme.md)
-
-## Development guide 
-
-- [Getting started](getting-started.md)
-- [Data ingestion](data-ingestion.md)
-- [Training data management](training-data-management.md)
-- [API documentation](api-documentation.md)
+- User documentation
+ + [User interface](curation_interface.md)
+ + [Curation workflow](curation_workflow.md)
+ + [Curation guidelines](guidelines/readme.md)
+
+- Development documentation
+ + [Getting started](getting-started.md)
+ + [Data ingestion](data-ingestion.md)
+ + [Training data management](training-data-management.md)
+ + [API documentation](api-documentation.md)