[MT] Added language around supernets (#22382)

* added language supernets

* refined text

Author: marciocloudflare

src/content/docs/magic-transit/how-to/advertise-prefixes.mdx

@@ -7,9 +7,11 @@ sidebar:
 
 import { Details, GlossaryTooltip } from "~/components"
 
-Cloudflare measures the Magic Transit <GlossaryTooltip term="prefix">prefix</GlossaryTooltip> count based on the number of prefixes a customer announces through Cloudflare. The size of the prefix does not matter; there is no commercial or technical restriction. However, prefixes can only be announced exactly as they were provisioned. For example, a `/20` prefix onboarded to Magic Transit can only be announced as a `/20`. Smaller subnets that constitute the `/20` cannot be announced individually. To announce 16 individual `/24s` subnets within the `/20` subnet mask, for example, requires onboarding all 16 subnets individually. If this disaggregated setup is desired, the total Magic Transit prefix count will increase.
+Cloudflare measures the Magic Transit prefix count based on the number of <GlossaryTooltip term="prefix">prefixes</GlossaryTooltip> a customer onboards. The size of each prefix does not matter — there are no commercial or technical restrictions based on prefix length. However, prefixes must be announced exactly as they were provisioned. For example, if a customer onboards a `/20` prefix to Magic Transit, it can only be announced as a `/20`. Smaller sub-prefixes (such as `/24s`) within that `/20` cannot be announced individually unless they are onboarded separately. Onboarding a larger aggregate prefix does not automatically include its smaller subnets for announcement or billing purposes.
 
-List all prefixes and the [autonomous systems (ASNs)](https://www.cloudflare.com/learning/network-layer/what-is-an-autonomous-system/) where they should originate. When specifying prefixes, observe these guidelines:
+If a customer wants to announce 16 individual `/24` prefixes that fall within a `/20`, they must onboard all 16 `/24s` as distinct prefixes, in addition to the `/20` if desired. In such a disaggregated setup, the total Magic Transit prefix count increases, as each onboarded prefix — including any sub-prefixes — is treated as a separate billable unit.
+
+Provide all IP prefixes you plan to onboard, along with the [Autonomous System Numbers (ASNs)](https://www.cloudflare.com/learning/network-layer/what-is-an-autonomous-system/) from which they will be advertised. When specifying prefixes, observe these guidelines:
 
 - Prefixes must support at least 256 hosts (`/24` in classless inter-domain [routing](https://www.cloudflare.com/learning/network-layer/what-is-routing/) CIDR notation). Refer to [Use a Cloudflare IP](/magic-transit/cloudflare-ips/) if you do not meet the `/24` prefix length requirement.
 - Internet Routing Registry entries and <GlossaryTooltip term="letter of agency">Letters of Agency (LOA)</GlossaryTooltip> must match the prefixes and originating prefixes you submit to Cloudflare.