Update InPageChannelProtocol description for clarity [skip ci]

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Author: posva

docs/content/8.references/5.browser-api.md

@@ -50,7 +50,7 @@ The values of `rpc.status`: [Handling connection and auth errors](/guide/client#
 
 The browser-only endpoint methods of the [in-page channel](/guide/in-page-channel). `emit()` sends to the opposite endpoint; `on()` handles events arriving from that endpoint.
 
-`InPageChannelProtocol` separates `functions` and `events`. Each section has optional `pageScript` and `panel` maps naming the receiving direction. Endpoint options require a complete `functions` map with handlers and a complete `events` map with optional handlers; use `{}` for empty maps. `call()` uses function names regardless of return type, while `emit()`, `callEvent()` (deprecated), and `on()` use event names. A function returning `void` or `Promise<void>` remains an awaitable request/response call.
+`InPageChannelProtocol` separates `functions` and `events`. Each section has optional `pageScript` and `panel` maps naming the receiving direction. Endpoint options require a complete `functions` map with handlers; `events` is optional, and when provided can include optional handlers (use `{}` to declare an event without a handler for `channel.on()`). `call()` uses function names regardless of return type, while `emit()`, `callEvent()` (deprecated), and `on()` use event names. A function returning `void` or `Promise<void>` remains an awaitable request/response call.
 
 | Method or property | Page-script endpoint | Panel endpoint |
 |--------------------|-------------|-------|