Node.js 18 EOL (#6165)

Author: MikeMcC399

docs/app/get-started/install-cypress.mdx

@@ -117,6 +117,7 @@ Cypress requires [Node.js](https://nodejs.org/) in order to install. We support
 
 Cypress generally aligns with
 [Node's release schedule](https://github.com/nodejs/Release).
+Accordingly, use of Node.js 18 with Cypress is deprecated and support is planned for removal in a future release of Cypress.
 
 #### Installing Node.js