add GetData

Author: trivalik

xml/System.Windows/Clipboard.xml

@@ -464,6 +464,7 @@
   
  ]]></format>
         </remarks>
+        <exception cref="T:System.Runtime.InteropServices.ExternalException">The Clipboard could not be opened. This typically occurs when the Clipboard is being used by another process.</exception>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="format" /> is <see langword="null" />.</exception>
         <altmember cref="M:System.Windows.Clipboard.GetAudioStream" />