readme.md in appium_lib-10.6.0 vs readme.md in appium_lib-11.0.0

@@ -19,10 +19,10 @@
 We can avoid the class driver with current `ruby_lib`, but if you'd like to implement your test cases based on instance driver, `@driver`, you can consider using `ruby_lib_core` first.
 
 # Setup
 ## Requirement
 - [Appium](https://github.com/appium/appium#requirements)
-- Ruby: 2.2+
+- Ruby: 2.4+
 
 ### Ruby Lib and Appium
 - Ruby library version over `9.8.0` requires Appium over `1.8`
 - Ruby library version under `9.7.5` can work with Appium under `1.7`