Updating .NET CHANGELOG for 2.39.0 release

Author: jimevans

dotnet/CHANGELOG

@@ -1,3 +1,24 @@
+v2.39.0
+=======
+ * Deprecated .NET AndroidDriver class. Going forward, the recommended approach
+ is to use a third-party implementation for Android, such as Selendroid
+ (http://selendroid.io/) or Appium (http://appium.io/).
+ * Added experimental IWebDriver extension methods to .NET support classes.
+ This commit adds extension methods to IWebDriver, which can be used to
+ reduce the amount of type casting that must be done to access
+ functionality not provided by the base IWebDriver interface. The following
+ methods were added:
+ 
+ * TakeScreenshot() - does not require a cast to ITakesScreenshot, and has
+ support for working directly with instances of RemoteWebDriver.
+ * ExecuteJavaScript<T>() - does not require a cast to
+ IJavaScriptExecutor, and will automatically cast the result to the type
+ specified by the generic type parameter (T).
+ 
+ These extension methods should be considered experimental. To use them
+ requires a reference to WebDriver.Support.dll, and adding a using clause
+ for OpenQA.Selenium.Support.Extensions.
+
 v2.38.0
 =======
  * Issue #6383: Adding method GetCSSCount to ISelenium.