prepare-docs: автоматически закрепляет index.md первым в сайдбаре

Добавлен Node-скрипт, который инжектит sidebar_position: 0
в front matter docs/index.md перед сборкой Docusaurus.

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

docusaurus/README.md

@@ -23,3 +23,19 @@ yarn build
 ```
 
 This command generates static content into the `build` directory and can be served using any static contents hosting service.
+
+## Deployment
+
+Using SSH:
+
+```bash
+USE_SSH=true yarn deploy
+```
+
+Not using SSH:
+
+```bash
+GIT_USER=<Your GitHub username> yarn deploy
+```
+
+If you are using GitHub pages for hosting, this command is a convenient way to build the website and push to the `gh-pages` branch.