docs: reword

Author: posva

docs/content/1.guide/12.in-page-channel.md

@@ -37,11 +37,13 @@ import type { InPageChannelProtocol } from 'devframe/in-page-channel'
 export const MY_CHANNEL = 'devframes:plugin:my-tool'
 
 export interface MyChannelProtocol extends InPageChannelProtocol {
-  pageScript: { // functions and events received by the page script
+  // implemented by the page script, callable by panels
+  pageScript: {
     highlight: (selector: string) => void
     measure: (selector: string) => { width: number, height: number }
   }
-  panel: { // functions and events received by panels
+  // implemented by panels, callable by the page script
+  panel: {
     flash: (message: string) => void
   }
   sharedStates: {