docs(realtime): use the new httpSend for REST broadcast (supabase#40227)

channel.send has been soft deprecated for REST broadcast usage

Author: edgurgel

apps/docs/spec/supabase_js_v2.yml

@@ -7375,12 +7375,7 @@ functions:
           ```js
           supabase
             .channel('room1')
-            .send({
-              type: 'broadcast',
-              event: 'cursor-pos',
-              payload: { x: Math.random(), y: Math.random()
-              },
-            })
+            .httpSend('cursor-pos', { x: Math.random(), y: Math.random() })
           ```
   - id: get-channels
     title: getChannels()