fix: next installation steps (#1685)

Author: brendan-defi

site/docs/pages/installation/nextjs.mdx

@@ -19,7 +19,7 @@ Create a new Next.js project by using the Next.js CLI.
 More information about Next.js can be found [here](https://nextjs.org/docs/getting-started/installation).
 
 ```bash [npm]
-npm create next-app@latest
+npx create-next-app@14
 ```
 
 During the setup process you will encounter multiple prompts.