docs: improved SEO of documentation (#3117)

* docs: added description to documentation pages

* docs: added more descriptions

* docs: finished improving meta description

* docs: added searchbox structured data

* docs: added breadcrumbs structured data

* docs: added how to structured data

* docs: improved 404 page

* docs: added how-to frontmatter option

docs/content/advanced/backend/subscribers/create-subscriber.md

@@ -1,4 +1,9 @@
-# Create a Subscriber
+---
+description: 'Learn how to create a subscriber in the Medusa server. You can use subscribers to implement functionalities like sending an order confirmation email.'
+addHowToData: true
+---
+
+# How to Create a Subscriber
 
 In this document, you’ll learn how to create a [Subscriber](overview.md) in your Medusa server that listens to events to perform an action.
 

docs/content/advanced/backend/subscribers/events-list.md

@@ -1,3 +1,7 @@
+---
+description: 'Learn about the available events and their data payloads in Medusa. Events can be used to perform an action when the events are triggered.'
+---
+
 # Events Reference
 
 This document details all events in Medusa, when they are triggered, and what data your handler method will receive when the event is triggered.

docs/content/advanced/backend/subscribers/overview.md

@@ -1,3 +1,7 @@
+---
+description: 'Learn what subscribers are in the Medusa server. Subscribers are used to listen to triggered events to perform an action.'
+---
+
 # Subscribers
 
 In this document, you'll learn what Subscribers are in Medusa.