docs: reference for server.moduleGraph in `per-environments-apis mi… (vitejs#2015)

resolve vitejs#2011

vitejs/vite@e2695b8 の反映です。

Author: shuuji3

changes/per-environment-apis.md

@@ -28,6 +28,6 @@ Vite v6 では、任意の数のカスタム環境（`client`、`ssr`、`edge` 
 
 ## 移行ガイド
 
-- `server.moduleGraph` -> [`environment.moduleGraph`](/guide/api-environment#separate-module-graphs)
+- `server.moduleGraph` -> [`environment.moduleGraph`](/guide/api-environment-instances#separate-module-graphs)
 - `server.transformRequest(url, ssr)` -> `environment.transformRequest(url)`
 - `server.warmupRequest(url, ssr)` -> `environment.warmupRequest(url)`