docs: use h3 instead

Author: atinux

docs/content/1.docs/1.getting-started/3.deploy.md

@@ -23,14 +23,14 @@ The [NuxtHub Admin](https://admin.hub.nuxt.com) is made to simplify your experie
 
 NuxtHub supports two types of deployments: production and preview.
 
-## Production Deployments
+### Production Deployments
 
 - When setting up your project, you can specify a production branch (defaults to `main`)
 - Successful deployments to the production branch will be:
   - Accessible via your primary domain
   - Also available at `<commit>.<project>.pages.dev`
 
-## Preview Deployments
+### Preview Deployments
 
 - Any deployment from a non-production branch (including pull requests) is considered a preview
 - Successful preview deployments are accessible via: