Add Echo and Gorm Docs

# Feature request

## Summary

Add Echo and Gorm Documentation to site
- Echo is a Backend Framework for Golang - https://echo.labstack.com/
- Gorm is an ORM for Golang - https://gorm.io/docs/

Start by reviewing the Echo and Gorm documentation links in the issue and the repository's existing process for adding API documentation sources. Done means both Echo and Gorm documentation are available on the DevDocs site.

由索引模型根据 Issue 内容生成。