Documented most valuable sentry options

Author: karser

README.md

@@ -88,6 +88,12 @@ Leaving this value empty (or undeclared) in other environments will effectively
 ```yaml
 sentry:
     dsn: "https://public:[email protected]/1"
+    options:
+        environment: '%kernel.environment%'
+        release: '%env(VERSION)%' #your app version
+        excluded_exceptions: #exclude validation errors
+            - App\Exception\UserNotFoundException
+            - Symfony\Component\Security\Core\Exception\AccessDeniedException
 ```
 
 #### Optional: use monolog handler provided by `sentry/sentry`