docs: environment API proposal

docs/.vitepress/config.ts

@@ -275,6 +275,10 @@ export default defineConfig({
               text: 'JavaScript API',
               link: '/guide/api-javascript',
             },
+            {
+              text: 'Vite Environment API',
+              link: '/guide/api-vite-environment',
+            },
             {
               text: 'Vite Runtime API',
               link: '/guide/api-vite-runtime',