Update dependencies (#1851)

vendor/github.com/slack-go/slack/README.md

@@ -39,7 +39,7 @@ func main() {
 	// If you set debugging, it will log all requests to the console
 	// Useful when encountering issues
 	// slack.New("YOUR_TOKEN_HERE", slack.OptionDebug(true))
-	groups, err := api.GetUserGroups(false)
+	groups, err := api.GetUserGroups(slack.GetUserGroupsOptionIncludeUsers(false))
 	if err != nil {
 		fmt.Printf("%s\n", err)
 		return
@@ -86,7 +86,13 @@ See https://github.com/slack-go/slack/blob/master/examples/websocket/websocket.g
 
 See https://github.com/slack-go/slack/blob/master/examples/eventsapi/events.go
 
+## Socketmode Event Handler (Experimental)
 
+When using socket mode, dealing with an event can be pretty lengthy as it requires you to route the event to the right place.
+
+Instead, you can use `SocketmodeHandler` much like you use an HTTP handler to register which event you would like to listen to and what callback function will process that event when it occurs.
+
+See [./examples/socketmode_handler/socketmode_handler.go](./examples/socketmode_handler/socketmode_handler.go)
 ## Contributing
 
 You are more than welcome to contribute to this project.  Fork and