To update documentation just place .md files in the guide folder. To edit the sidebar list titles you have to edit the title field in .md file. If a subfolder doesn't provide a README.md file with the title section, the system will use folder name for the title.
To generate static files run npm run docs:build the files are stored in the .vuepress/dist folder. You can use serve package to run them in your browser.
To run the script in development mode run npm run docs:dev. This mode watches all of the files except the .md files. To watch the .md files run npm run dev:watch.