README.md in minato-trace-0.1.6.pre.2 vs README.md in minato-trace-0.1.6.pre.3

@@ -31,9 +31,11 @@
 ```ruby
 {ServiceClass}.configure do |config|
   config.use Minato::Trace::Middleware::DistributedTraceContext
 end
 ```
+## Disable trace
+Trace is enabled by default. If you want to disable trace, set an environment variable `MINATO_TRACE_DISABLE=true` in your app.
 
 ## Changelog
 Changelog information could be found [here](CHANGELOG.md).
 
 ## License