fix(docs): retarget docs-home Introduction links to why-deerflow (temporary) (#4916)

frontend/src/content/en/index.mdx

@@ -20,7 +20,7 @@ If you want to understand how DeerFlow works, start with the Introduction. If yo
 
 Start with the conceptual overview first.
 
-- [Introduction](./docs/introduction)
+- [Introduction](./docs/introduction/why-deerflow)
 - [Why DeerFlow](./docs/introduction/why-deerflow)
 - [Harness vs App](./docs/introduction/harness-vs-app)
 
@@ -89,7 +89,7 @@ The Reference section is for detailed lookup material, including configuration,
 
 ## Choose the right path
 
-- If you are **evaluating the project**, start with [Introduction](./docs/introduction).
+- If you are **evaluating the project**, start with [Introduction](./docs/introduction/why-deerflow).
 - If you are **building your own agent system**, start with [DeerFlow Harness](./docs/harness).
 - If you are **deploying DeerFlow for users**, start with [DeerFlow App](./docs/application).
 - If you want to **learn by doing**, go to [Tutorials](./docs/tutorials/first-conversation).

frontend/src/content/zh/index.mdx

@@ -20,7 +20,7 @@ DeerFlow 是一个用于构建和运行 Agent 系统的框架。它提供了一
 
 先从概念概述开始。
 
-- [简介](./docs/introduction)
+- [简介](./docs/introduction/why-deerflow)
 - [为什么选择 DeerFlow](./docs/introduction/why-deerflow)
 - [Harness 与应用的区别](./docs/introduction/harness-vs-app)