README.md in tobox-0.4.2 vs README.md in tobox-0.4.3

@@ -476,9 +476,13 @@
 Plugin for the [sentry](https://github.com/getsentry/sentry-ruby) ruby SDK for error tracking. It'll send all errors happening while processing events to Sentry.
 
 ```ruby
 # tobox.rb
 plugin(:sentry)
+
+on_sentry_init do |sentry_cfg|
+  sentry.dsn = ENV["SENTRY_DSN"]
+end
 ```
 
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 ### Datadog