README.md in zeebe-client-0.7.0 vs README.md in zeebe-client-0.8.0

- old
+ new

@@ -11,10 +11,10 @@
     gem install zeebe-client
 
 Run a Zeebe instance locally:
 
 ```sh
-docker run -it --rm -p 26500:26500 camunda/zeebe:0.20.0
+docker run -it --rm -p 26500:26500 camunda/zeebe:0.21.1
 ```
 
 And then try the available [demo script](examples/demo.rb).
 
 See the [changelog](CHANGELOG.md) before upgrading.