docs: improve environment variables part (#478)

Author: OlivierBelaud

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

@@ -210,16 +210,19 @@ NuxtHub automatically copies all your project's environment variables to your Gi
 
 When encrypting an environment variable in the NuxtHub Admin, a GitHub actions secret will be created in your repository.
 
+You can view the environment variables and secrets synchronized by NuxtHub by navigating to **Repository Settings -> Secrets and variables -> Actions** on GitHub.
+
 ::warning
-If you have a private repository on a free GitHub account or organization, NuxtHub won't be able to sync the env variables & secrets as GitHub repository environments (production / preview) are not available.
+If you have a private repository on a free GitHub account or organization, NuxtHub won't be able to sync the env variables & secrets as GitHub repository environments (production / preview) are not available. In this case, you must manually set up the environment variables by navigating to **Repository Settings -> Secrets and variables -> Actions** on GitHub.
 ::
 
-In order to use GitHub Actions secret, you need to update the GitHub Actions workflow to use the secret as environment variable:
+In order to use GitHub Actions variables and secrets, you need to update your workflow to expose them as environment variables:
 
 ```diff [.github/workflows/nuxthub.yml]
   - name: Build application
     run: pnpm run build
 +   env:
++     NUXT_PUBLIC_VAR: ${{ vars.NUXT_PUBLIC_VAR }}
 +     NUXT_UI_PRO_LICENSE: ${{ secrets.NUXT_UI_PRO_LICENSE }}
 ```