custom subdomain instructions added

doc/user-guide/custom-domains.md

@@ -21,49 +21,73 @@ If you would like a custom `ploomberapp.io` subdomain, like `my-custom-app.ploom
 
 ### Adding a custom subdomain
 
-To deploy an app at `subdomain.yourdomain.com`, you first need to ensure it's deployed and available (the **VIEW APPLICATION** button should be enabled)
+To deploy an app at `subdomain.yourdomain.com`, you first need to ensure the main domain you want to link to (e.g., `yourdomain.com`) is registered properly. 
+
+There are 2 ways to register the main domain:
+
+1. [Connect to a running app](new-custom-domain-with-app)
+2. [Create a global domain that is not connected to any app](new-custom-domain-no-app)
+
+Once we have the main domain registered, we can go to the application settings page by clicking on the **SETTINGS** button. 
 
 ![](../static/custom-domains/view-application.png)
 
+
+Next, in the **Custom domains** section, click the text field and you should see your new domain there. It means the domain is available, and you can host your application on a subdomain of it.
+
+![](../static/custom-domains/subdomain-settings.png)
+
+
 ```{warning}
-If your application is not ready and publicly available, the button will be disabled and you won't be able to connect a custom domain to it.
+If you don't see your main domain in there, it means something went wrong and you probably won't be able to use a subdomain. In this case, please contact us via [contact@ploomber.io](mailto:contact.ploomber.io) or our public [slack channel](https://ploomber.io/community/)
 ```
 
-Go to the application settings page by clicking on the **SETTINGS** button. Next, in the **Custom domains** section, enter your domain name and click **CONNECT**.
 
-![](../static/custom-domains/custom-subdomain-section.png)
+1. Select the domain, type your subdomain (e.g., `app.example.com`), and click connect
 
+![](../static/custom-domains/subdomain-settings-selected.png)
 
-A new section will display. **Disregard its contents**, and follow these instructions.
+2. Once the subdomain is registered successfully, please complete the process by [updating your DNS records](update-dns-records)
 
-Add the following records:
+![](../static/custom-domains/subdomain-dns.png)
 
-1. `CNAME` record: set `subdomain` as the host (e.g., if you want to serve from `subdomain.example.com` set `subdomain`) and set the value to `{yourapp}.ploomberapp.io`.
-2. `CNAME` record: with the shown **CNAME name** and **CNAME value** (as displayed in the **SSL certification status** section, see below)
 
-![](../static/custom-domains/ssl-cname-record.png)
+(new-custom-domain-no-app)=
+#### New custom domain without an app 
 
-To modify your DNS records, follow these instructions (they apply to Namecheap but they're similar for other DNS providers):
+Users have the option to create custom domains without associating them directly with any specific application. This option allows users to host multiple applications under different subdomains, such as `app1.example.com`, `app2.example.com`, and `app3.example.com`, while the main domain, `example.com`, remains independent of any hosted application.
 
-1. Log in to your [Namecheap account](https://www.namecheap.com/)
+1. Go to `Account` section 
 
-2. Click `Domain List` tab and then click `Manage` button next to your domain
+![](../static/custom-domains/navigation-bar.png)
 
-![](../static/custom-domains/namecheap-domains.png)
+2. In the `Domains` section, you can view your registered domains. Currently, there are no registered domains.
+To add a new domain, click on `NEW DOMAIN` and wait for the popup.
 
-3. Click `Advanced DNS`
+![](../static/custom-domains/domains-section.png)
 
-![](../static/custom-domains/namecheap-advanced-dns.png)
+3. Type your main domain, e.g., `example.com` and click `CREATE`
 
-4. Add the relevant DNS records, and click `Save all changed`.
+![](../static/custom-domains/new-global-domain-popup.png)
 
+4. Once it's done you should be able to see your new domain under `Domains`
 
-```{important}
-DNS record changes might take up to 48 hours to take effect. In the meantime, your application will be accessible from the `ploomberapp.io` URL
-```
+![](../static/custom-domains/domains-section-with-domain.png)
+
+5. Update your DNS records
+
+First, open the information panel by clicking this icon next to your domain: ![](../static/custom-domains/info-icon.png)
+
+![](../static/custom-domains/global-domains-sidebar.png)
+
+As you can see, the domain has been created, and there is no attached application.
+To make the domain availble via SSL, we need to add one DNS record as described in the information panel.
+
+Please follow these instructions on how to [update your DNS records](update-dns-records)
 
 
-### Adding a custom domain
+(new-custom-domain-with-app)=
+#### Adding a custom domain
 
 To deploy an app at `yourdomain.com`, you first need to ensure it's deployed and available (the **VIEW APPLICATION** button should be enabled)
 
@@ -84,7 +108,7 @@ There are two ways to connect a custom domain. Depending on where you want to st
 
 
 
-#### Method 1: CNAME record
+##### Method 1: CNAME record
 
 After typing your domain and clicking on **CONNECT**, a window like this will display:
 
@@ -99,6 +123,7 @@ These are the three records you need to add:
 
 ![](../static/custom-domains/ssl-cname-record.png)
 
+(update-dns-records)=
 To modify your DNS records, follow these instructions (they apply to Namecheap but they're similar for other DNS providers):
 
 1. Log in to your [Namecheap account](https://www.namecheap.com/)
@@ -122,7 +147,7 @@ You should be able to see something like this:
 DNS record changes might take up to 48 hours to take effect. In the meantime, your application will be accessible from the `ploomberapp.io` URL
 ```
 
-#### Method 2: Nameservers
+##### Method 2: Nameservers
 
 First, let's change the connection method to nameservers, by clicking `nameservers`.