Adds clarification about available settings (#18498)

Author: angelampcosta

src/content/docs/spectrum/get-started.mdx

@@ -12,6 +12,8 @@ Spectrum is available on all paid plans. Pro and Business support selected proto
 
 To create a Spectrum application, you can either use an IP address, a CNAME Record or a load balancer. Independently of the method you use, you can create the application through the dashboard or via [API](/api/operations/spectrum-applications-list-spectrum-applications).
 
+Certain fields in Spectrum request and response bodies require an Enterprise plan. Refer to the [Settings by plan](/spectrum/reference/settings-by-plan/) page for more details.
+
 ## Create a Spectrum application using an IP address
 
 To create a Spectrum application using an IP address, Cloudflare normally assigns you an arbitrary IP from Cloudflare’s IP pool to your application. If you want to use your own IP addresses, you can use [BYOIP](/spectrum/about/byoip/) or you can also use a [Static IP](/spectrum/about/static-ip/). In these two last cases, you need to create your Spectrum application through the API, as these features are not available via dash. When using the API, the field `origin_direct` takes as input the IP address.