feat: add header with version and changelog link

Author: carlosala

vocs.config.tsx

@@ -1,5 +1,7 @@
 import { defineConfig } from "vocs"
 
+const version = "1.10.0"
+
 export default defineConfig({
   title: "Polkadot-API",
   description: "Typescript API to interact with polkadot chains",
@@ -9,6 +11,15 @@ export default defineConfig({
       text: "Guide",
       link: "/getting-started",
     },
+    {
+      text: `${version}`,
+      items: [
+        {
+          text: "Changelog",
+          link: `https://github.com/polkadot-api/polkadot-api/releases/tag/polkadot-api${encodeURIComponent("@")}${version}`,
+        },
+      ],
+    },
   ],
   sidebar: [
     {