Update docs: custom domain dns setup

nbs/how_to/02_add_custom_domain.ipynb

@@ -22,8 +22,14 @@
     "On this page you will learn how to customize your app's domain in two ways:\n",
     "\n",
     "1. Custom pla.sh subdomain\n",
-    "2. Bring your own domain\n",
-    "\n",
+    "2. Bring your own domain"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "63ea66e0",
+   "metadata": {},
+   "source": [
     "## Custom pla.sh subdomain\n",
     "\n",
     "When you deploy a Plash app for the first time, a `.plash` file is created in your project root directory. This file contains your app's configuration, including the app name which determines your subdomain:\n",
@@ -53,55 +59,60 @@
     "\n",
     "::: {.callout-tip}\n",
     "You cannot choose a `PLASH_APP_NAME` that has been taken by another user. If you do, you'll receive an error when you run plash_deploy.\n",
-    ":::\n",
-    "\n",
-    "\n",
+    ":::"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "2ce6027a",
+   "metadata": {},
+   "source": [
     "## Using Your Own Custom Domain\n",
     "\n",
     "To use your own domain with your Plash app:\n",
     "\n",
     "1. Open the `.plash` file in your project directory\n",
     "2. Replace the `PLASH_APP_NAME` value with your full domain name\n",
-    "3. Set up a CNAME record with your DNS provider pointing to `pla.sh`\n",
+    "3. Set up DNS to point to `pla.sh` (see below)\n",
     "4. Redeploy your app with `plash_deploy`\n",
     "\n",
     "```bash\n",
     "# Example .plash file with custom domain\n",
     "export PLASH_APP_NAME='myapp.example.com'\n",
     "```\n",
     "\n",
-    "### Setting Up DNS Records\n",
-    "\n",
-    "You'll need to create a CNAME record with your DNS provider that points your domain to `pla.sh`. Here are quick guides for popular DNS providers:\n",
+    "### Setting Up DNS\n",
     "\n",
-    "#### Cloudflare\n",
-    "1. Log in to your Cloudflare dashboard\n",
-    "2. Select your domain\n",
-    "3. Go to the DNS tab\n",
-    "4. Add a CNAME record:\n",
-    "   - Type: CNAME\n",
-    "   - Name: Your subdomain (or @ for root domain)\n",
-    "   - Target: pla.sh\n",
-    "   - TTL: Auto\n",
+    "**For subdomains** (e.g., `app.example.com`): Create a CNAME record pointing to `pla.sh`.\n",
     "\n",
-    "For detailed instructions, see the [Cloudflare DNS setup guide](https://developers.cloudflare.com/dns/zone-setups/partial-setup).\n",
+    "**For apex/root domains** (e.g., `example.com`): Standard CNAME records won't work. You need a provider that supports CNAME flattening or ALIAS records:\n",
     "\n",
-    "#### Namecheap\n",
-    "1. Log in to your Namecheap account\n",
-    "2. Go to Domain List and click \"Manage\" next to your domain\n",
-    "3. Navigate to the \"Advanced DNS\" tab\n",
-    "4. Add a CNAME record:\n",
-    "   - Type: CNAME Record\n",
-    "   - Host: Your subdomain (or @ for root domain)\n",
-    "   - Value: pla.sh\n",
-    "   - TTL: Automatic\n",
+    "| Provider | Record Type |\n",
+    "|----------|-------------|\n",
+    "| Cloudflare | CNAME (auto-flattened at apex) |\n",
+    "| AWS Route 53 | ALIAS |\n",
+    "| Azure DNS | Alias |\n",
+    "| DNS Made Easy | ANAME |\n",
+    "| DNSimple | ALIAS |\n",
+    "| Namecheap | ALIAS |\n",
+    "| Porkbun | ALIAS |\n",
     "\n",
-    "For detailed instructions, see the [Namecheap CNAME setup guide](https://www.namecheap.com/support/knowledgebase/article.aspx/9646/2237/how-to-create-a-cname-record-for-your-domain/).\n",
+    "::: {.callout-tip}\n",
+    "We recommend **Cloudflare** for DNS—just create a CNAME at the apex and it handles flattening automatically.\n",
+    ":::\n",
     "\n",
-    "::: {.callout-note}\n",
-    "DNS changes can take up to 48 hours to propagate fully, though they often take effect much sooner.\n",
+    "::: {.callout-warning}\n",
+    "GoDaddy does not support CNAME flattening. Use a subdomain or switch DNS providers.\n",
     ":::\n",
     "\n",
+    "DNS changes can take up to 48 hours to propagate, though they often take effect much sooner."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "d034f19f",
+   "metadata": {},
+   "source": [
     "## Verifying Your Custom Domain\n",
     "\n",
     "After setting up your custom domain and redeploying your app, you can verify it's working by:\n",
@@ -111,13 +122,7 @@
    ]
   }
  ],
- "metadata": {
-  "kernelspec": {
-   "display_name": "python3",
-   "language": "python",
-   "name": "python3"
-  }
- },
+ "metadata": {},
  "nbformat": 4,
  "nbformat_minor": 5
 }