docs: Add Note message to README (#531)

* Add Note message to README

Since it seems to be confusion among users about which version they should use, a note message can do only good.

Author: Dor-bl

README.md

@@ -8,6 +8,12 @@
 This driver is an extension of the [Selenium](http://docs.seleniumhq.org/) C# client. It has 
 all the functionalities of the regular driver, but add Appium specific methods on top of this.
 
+> **Note**
+>
+> The last stable version(v4.3.2) supports the legacy Selenium 3.150.0.<br/>	 
+> In case you would like to use this client with Selenium 4.0 and above, please use the latest beta version(v5.0.0). <br/>
+> We are well aware this project is not activly maintained, therefore any contributors are more than welcomed to assist with this project.
+
 ## NuGet
 
 NuGet Package: [](http://www.nuget.org/packages/Appium.WebDriver/)