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/usage/create-medusa-app.mdx

@@ -1,3 +1,8 @@
+---
+description: 'Learn how to create a composable commerce platform using Medusa. This quickstart guide will help you set up your Medusa server, admin, and storefront all at once.'
+addHowToData: true
+---
+
 import Tabs from '@theme/Tabs';
 import TabItem from '@theme/TabItem';
 import Feedback from '@site/src/components/Feedback';