[Magic Firewall] Add MWAN support (#19834)

Author: Maddy-Cloudflare

src/content/docs/magic-firewall/how-to/enable-ids.mdx

@@ -82,6 +82,7 @@ Similarly, sending a patch request with the `enabled` field set to `true` will e
 
 IDS rules are run on a subset of packets. IDS also supports the current flows:
 
+- Magic WAN to Magic WAN.
 - Magic Transit ingress traffic (when egress traffic is handled through direct server return).
 - Magic Transit ingress and egress traffic when Magic Transit has the [Egress option enabled](/reference-architecture/architectures/magic-transit/#magic-transit-with-egress-option-enabled).