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/DiscountConditionCustomerGroup.mdx

@@ -12,7 +12,7 @@ Associates a discount condition with a customer group
 
 ### constructor
 
-**new DiscountConditionCustomerGroup**()
+`**new DiscountConditionCustomerGroup**()`
 
 Associates a discount condition with a customer group
 
@@ -39,8 +39,8 @@ Associates a discount condition with a customer group
   },
   {
     "name": "customer_group",
-    "type": "[`CustomerGroup`](CustomerGroup.mdx)",
-    "description": "Available if the relation `customer_group` is expanded.",
+    "type": "[CustomerGroup](CustomerGroup.mdx)",
+    "description": "Available if the relation `customer\\_group` is expanded.",
     "optional": true,
     "defaultValue": "",
     "expandable": false,
@@ -57,8 +57,8 @@ Associates a discount condition with a customer group
   },
   {
     "name": "discount_condition",
-    "type": "[`DiscountCondition`](DiscountCondition.mdx)",
-    "description": "Available if the relation `discount_condition` is expanded.",
+    "type": "[DiscountCondition](DiscountCondition.mdx)",
+    "description": "Available if the relation `discount\\_condition` is expanded.",
     "optional": true,
     "defaultValue": "",
     "expandable": false,
@@ -66,7 +66,7 @@ Associates a discount condition with a customer group
   },
   {
     "name": "metadata",
-    "type": "Record<`string`, `unknown`\\>",
+    "type": "`Record<string, unknown>`",
     "description": "An optional key-value map with additional details",
     "optional": false,
     "defaultValue": "",