docs: update to node 18 (#3689)

## About the changes
Update documentation to the minimum version of node. This was already
updated in other parts of the documentation

---------

Co-authored-by: Thomas Heartman <thomas@getunleash.io>

website/docs/reference/deploy/getting-started.md

@@ -8,7 +8,7 @@ title: Getting Started
 
 You will need:
 
-- [Node.js](https://nodejs.org/en/download/) (version 14 or later)
+- [Node.js](https://nodejs.org/en/download/) (version 18 or later)
 - [PostgreSQL](https://www.postgresql.org/download/) (version 10 or later)
 - [Create an unleash user and database](./database-setup).
 

website/package.json

@@ -3,7 +3,7 @@
   "version": "0.0.0",
   "private": true,
   "engines": {
-    "node": ">=16.14"
+    "node": ">=18"
   },
   "scripts": {
     "docusaurus": "docusaurus",