docs: redesigned code blocks (#2745)

* docs: redesigned code blocks to include titles

* docs: added a title where necessary

docs/content/add-plugins/s3.md

@@ -108,7 +108,7 @@ Where:
 
 Finally, in `medusa-config.js`, add to the `plugins` array the following new item:
 
-```jsx
+```jsx title=medusa-config.js
 const plugins = [
   //...
   {
@@ -156,7 +156,7 @@ If this configuration is not added, you’ll receive the error ["next/image Un-
 
 In `next.config.js` add the following option in the exported object:
 
-```jsx
+```jsx title=next.config.js
 const { withStoreConfig } = require("./store-config")
 
 //...