[WAF] Clarify custom block response availability (cloudflare#22902)

Author: pedrosousa

src/content/docs/waf/custom-rules/create-dashboard.mdx

@@ -33,6 +33,10 @@ import { Render } from "~/components";
 
 ## Configure a custom response for blocked requests
 
+:::note
+This feature is only available on paid plans.
+:::
+
 <Render
 	file="custom-response-blocked-requests"
 	params={{

src/content/docs/waf/rate-limiting-rules/create-zone-dashboard.mdx

@@ -45,6 +45,10 @@ import { Render } from "~/components";
 
 ## Configure a custom response for blocked requests
 
+:::note
+This feature is only available on paid plans.
+:::
+
 <Render
 	file="custom-response-blocked-requests"
 	params={{