improve documentation

Author: willswire

README.md

@@ -13,7 +13,7 @@ You must have a Cloudflare account and your domain must be configured to point t
 2. 'Quick Edit' the worker within your browser.
 3. Copy and paste the contents of [index.js](https://github.com/willswire/unifi-cloudflare-ddns/blob/main/index.js) into the code editor for your worker. Ensure that you are replacing any boilerplate/code that is currently there. 
 4. Once you have created the worker, take note of it's \*.workers.dev route. More on routes for Cloudflare Workers [here](https://developers.cloudflare.com/workers/platform/routes#routes-with-workersdev).
-5. Create an API token so the Worker can update your DNS records. Go to https://dash.cloudflare.com/profile/api-tokens and select "Create custom token". Enable permissions for both **Zone:Read** and **DNS:Edit**. Copy your API Key - you will need it later when configuring your UniFi OS Controller.
+5. Create an API token so the Worker can update your DNS records. Go to https://dash.cloudflare.com/profile/api-tokens and select "Create token". On the next page, scroll down and click the "Get Started" button next to the "Create Custom Token" label. Select **Zone:DNS:Edit** for the "Permissions" drop-down, and include your target zone under the "Zone Resources" drop-down. Copy your API Key - you will need it later when configuring your UniFi OS Controller.
 
 ### Configuring UniFi OS
 1. Log on to your [UniFi OS Controller](https://unifi.ui.com/)
@@ -25,6 +25,6 @@ You must have a Cloudflare account and your domain must be configured to point t
 - `Password`: the Cloudflare API Token you created earlier
 - `Server`: the Cloudflare Worker route `<worker-name>.<worker-subdomain>.workers.dev/update?ip=%i&hostname=%h`. 
 
-#### Important Note!
-On UniFi devices older than the UDM, the `Server` value should be configured as seen below, with no path suffix: 
-- `<worker-name>.<worker-subdomain>.workers.dev`
+#### Important Notes!
+- If you are attempting to update a subdomain (`sub.example.com`), you must manually create an A record for it **first** in your Cloudflare dashboard.
+- On UniFi devices older than the UDM, the `Server` value should be configured as seen below, with no path suffix: `<worker-name>.<worker-subdomain>.workers.dev`