Index the installation documents better.
site_name: KGTK documentation
nav:
- Home: index.md
- - Getting started: install.md
+ - 'Getting Started':
+ -- 'Installing KGTK': install.md
+ -- 'Installing KGTK: Details': install-details.md
- KGTK data model: data_model.md
- KGTK file specification: specification.md
- KGTK environment variables: envars.md
