Merge pull request #45 from heroku/bernerdschaefer-patch-1

Update README.md

README.md

@@ -4,9 +4,11 @@
 
 Rollrus is what happens when [Logrus](https://github.com/sirupsen/logrus) meets [Rollbar](github.com/rollbar/rollbar-go).
 
-When a .Error, .Fatal or .Panic logging function is called, report the details to Rollbar via a Logrus hook.
+Install the hook into a Logrus logger to report logged messages to Rollbar.
+By default, only messages with the Error, Fatal, or Panic level are reported.
 
-Delivery is synchronous to help ensure that logs are delivered.
+Panic and Fatal errors are reported synchronously to help ensure that logs are delivered before the process exits.
+All other messages are delivered in the background, and may be dropped if the queue is full.
 
 If the error includes a [`StackTrace`](https://godoc.org/github.com/pkg/errors#StackTrace), that `StackTrace` is reported to rollbar.