docs: document admin environment variables (#11313)

www/apps/resources/app/js-sdk/page.mdx

@@ -48,8 +48,8 @@ For admin customizations, create this file at `src/admin/lib/config.ts`.
 import Medusa from "@medusajs/js-sdk"
 
 export const sdk = new Medusa({
-  baseUrl: "http://localhost:9000",
-  debug: process.env.NODE_ENV === "development",
+  baseUrl: import.meta.env.VITE_BACKEND_URL || "/",
+  debug: import.meta.env.DEV,
   auth: {
     type: "session",
   },
@@ -78,6 +78,12 @@ export const sdk = new Medusa({
   </CodeTab>
 </CodeTabs>
 
+<Note title="Tip">
+
+In the Medusa Admin you use `import.meta.env` to access environment variables becaues the Medusa Admin is built on top of [Vite](https://vitejs.dev/). Learn more in [this documentation](!docs!/learn/fundamentals/admin/environment-variables).
+
+</Note>
+
 ### JS SDK Configurations
 
 The `Medusa` initializer accepts as a parameter an object with the following properties: