docs: update docusaurus to v3 (#5625)

* update dependencies

* update onboarding mdx

* fixes for mdx issues

* fixes for mdx compatibility

* resolve mdx errors

* fixes in reference

* fix check errors

* revert change in vale action

* fix node version in action

* fix summary in markdown

www/apps/docs/content/references/services/classes/FulfillmentProvider.mdx

@@ -12,7 +12,7 @@ A fulfillment provider represents a fulfillment service installed in the Medusa
 
 ### constructor
 
-**new FulfillmentProvider**()
+`**new FulfillmentProvider**()`
 
 A fulfillment provider represents a fulfillment service installed in the Medusa backend, either through a plugin or backend customizations. It holds the fulfillment service's installation status.
 
@@ -31,7 +31,7 @@ A fulfillment provider represents a fulfillment service installed in the Medusa
   {
     "name": "is_installed",
     "type": "`boolean`",
-    "description": "Whether the fulfillment service is installed in the current version. If a fulfillment service is no longer installed, the `is_installed` attribute is set to `false`.",
+    "description": "Whether the fulfillment service is installed in the current version. If a fulfillment service is no longer installed, the `is\\_installed` attribute is set to `false`.",
     "optional": false,
     "defaultValue": "true",
     "expandable": false,