2 Understand the Structure
Know which small set of files owns configuration, content, and deployment.
The starter keeps each responsibility in one obvious place.
The map
Navigation follows content
The menus.main front matter on each section root creates the top navigation and its dropdowns. The directory tree below Docs and Book creates their sidebars.
Translations stay together
English uses .md; Chinese and French peers use .zh.md and .fr.md. Keep the files side by side and use matching explicit heading IDs.