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/Country.mdx

@@ -12,7 +12,7 @@ Country details
 
 ### constructor
 
-**new Country**()
+`**new Country**()`
 
 Country details
 
@@ -75,7 +75,7 @@ Country details
   },
   {
     "name": "region",
-    "type": "[`Region`](Region.mdx)",
+    "type": "[Region](Region.mdx)",
     "description": "The details of the region the country is associated with.",
     "optional": false,
     "defaultValue": "",