Added a redirect for the functions page movement (#1319)

next.config.js

@@ -8,6 +8,11 @@ const withFonts = require('next-fonts');
 
 async function redirects() {
   return [
+    {
+      source: '/references/language-functions',
+      destination: '/write-smart-contracts/language-functions',
+      permanent: true,
+    },
     {
       source: '/write-smart-contracts/nft',
       destination: '/write-smart-contracts/nft-tutorial',