Update client-generator/nextjs.md

Co-Authored-By: Kévin Dunglas <[email protected]>

Author: Gregcop1

client-generator/nextjs.md

@@ -84,7 +84,7 @@ $ yarn dev
 
 and access it through `http://localhost:3000`
 
-## Generating routes
+## Generating Routes
 
 ```bash
 $ npx @api-platform/client-generator https://demo.api-platform.com src/ -g next --resource book