docs: add note about preview and prod deployments

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

@@ -19,6 +19,27 @@ The [NuxtHub Admin](https://admin.hub.nuxt.com) is made to simplify your experie
 ::
 ::
 
+## Production vs Preview Deployments
+
+NuxtHub supports two types of deployments: production and preview.
+
+## 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
+
+- Any deployment from a non-production branch (including pull requests) is considered a preview
+- Successful preview deployments are accessible via:
+  - `<commit>.<project>.pages.dev`
+  - `<branch>.<project>.pages.dev`
+
+::tip
+Toggle between production and preview environments in the NuxtHub admin using the "Preview mode" switch.
+::
 
 ## NuxtHub CLI