style: explain the configuration function of envPrefix in vite (#2865)

Author: RSS1102

src/content/docs/start/frontend/vite.mdx

@@ -104,7 +104,7 @@ This guide is accurate as of Vite 5.4.8.
         host: host || false,
         port: 5173,
       },
-      // to access the Tauri environment variables set by the CLI with information about the current target
+      // Env variables starting with the item of `envPrefix` will be exposed in tauri's source code through `import.meta.env`.
       envPrefix: ['VITE_', 'TAURI_ENV_*'],
       build: {
         // Tauri uses Chromium on Windows and WebKit on macOS and Linux