Update README.md

Updated link for Appium documentation (previously broken).

Author: hassanuz

README.md

@@ -214,7 +214,7 @@ Windows Application Driver is integrated with Appium, meaning if you use Appium
 2. To create multiple sessions with one Appium server you need Appium 1.6.4 or newer
 3. When pointing a test at Appium you need to include `/wd/hub` on the server URI. E.g. `http://127.0.0.1:4723/wd/hub`
 
-For more details visit the Appium documentation: <http://appium.io/slate/en/master/?ruby#windows-application-ui-testing>
+For more details visit the Appium documentation: <https://appium.io/docs/en/drivers/windows/>
 
 
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