Document the OAuth scopes required by the Slack toolkit (#344)

list scopes required by the slack toolkit

Author: byrro

pages/home/auth-providers/slack.mdx

@@ -36,7 +36,21 @@ Before showing how to configure your Slack app credentials, let's go through the
 </Warning>
 
 - Follow Slack's guide to [registering a Slack app](https://api.slack.com/quickstart)
-- Choose the scopes (permissions) you need for your app
+- If you plan to use the [Arcade Slack toolkit](/toolkits/social-communication/slack), select the scopes below (include additional scopes for your application's authorization needs or custom tools, in any):
+  - `channels:history`
+  - `channels:read`
+  - `chat:write`
+  - `groups:read`
+  - `groups:history`
+  - `groups:write`
+  - `im:history`
+  - `im:read`
+  - `im:write`
+  - `mpim:history`
+  - `mpim:read`
+  - `mpim:write`
+  - `users:read`
+  - `users:read.email`
 - Set the redirect URL to: `https://cloud.arcade.dev/api/v1/oauth/callback`
 - Copy the client ID and client secret