docs: comments

Author: posva

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

@@ -38,13 +38,20 @@ export const MY_CHANNEL = 'devframes:plugin:my-tool'
 
 export interface MyChannelProtocol extends InPageChannelProtocol {
   functions: {
+    /** implemented by the page script, callable by panels */
     pageScript: {
       measure: (selector: string) => { width: number, height: number }
       reset: () => Promise<void>
     }
+    /** implemented by panels, callable by the page script */
+    panel: {
+      echo: (message: string) => Promise<string>
+    }
   }
   events: {
+    /** listened to by the page script, emitted by panels */
     pageScript: { highlight: (selector: string) => void }
+    /** listened to by panels, emitted by the page script */
     panel: { flash: (message: string) => void }
   }
   sharedStates: {