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/migrations/index.md

@@ -1,3 +1,8 @@
+---
+description: 'Learn how to create a migration in the Medusa server. This guide explains how to write and run migrations.'
+addHowToData: true
+---
+
 # How to Create Migrations
 
 In this document, you’ll learn how to create a [Migration](overview.md) using [Typeorm](https://typeorm.io) on your Medusa server.

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

@@ -1,3 +1,7 @@
+---
+description: 'Learn what Migrations are in the Medusa server and how to run them. Migrations are used to make changes to the database schema the Medusa server is linked to.'
+---
+
 # Migrations
 
 In this document, you'll learn what Migrations are in Medusa.