docs(config): update site title and description

Update the site's title and description to more accurately reflect the capabilities and focus of ArchGuard. This change enhances the clarity and appeal of the site's introduction.

- Title is expanded to include "微服务时代的架构分析、可视化、治理工具", emphasizing the tool's relevance and features.
- Description is enriched to detail ArchGuard's purpose in microservices/distributed scenarios, including its role in architecture analysis, visualization, and governance.

_config.yml

@@ -1,7 +1,7 @@
 #theme: just-the-docs
 remote_theme: pmarsceill/just-the-docs
 
-title: ArchGuard 架构治理
+title: ArchGuard 架构治理 - 微服务时代的架构分析、可视化、治理工具
 description: ArchGuard 是一个针对于微服务（分布式场景）下的架构工作台/治理工具。它可以帮助架构师、开发人员进行架构自助，自定义架构的洞察、分析系统间的远程服务依赖情况、数据库依赖、API 依赖等。并根据一些架构治理模型，对现有系统提出改进建议。
 
 heading_anchors: true