fix: even more readme

packages/spacecat-shared-rum-api-client/README.md

@@ -22,6 +22,8 @@ To configure tokens for your application, follow these steps:
 
 3. Locate your Slack bot token under the "Bot User OAuth Token" section on the same page. You will need to provide this token to the `SlackClient` in your application.
 
+4. For information on the scopes needed for each Slack API method, refer to the [documentation](https://api.slack.com/methods). The required scopes for each API method are listed in the "Bot tokens" row. As an example, to use the `postMessage` API method, the required scope is `chat:write`, as documented in [https://api.slack.com/methods/chat.postMessage](https://api.slack.com/methods/chat.postMessage).
+
 ### Creating and instance from Helix UniversalContext
 
 ```js