Fix a doc copy-pasto(?? (#7758)

The docs for BeginOpen said "close" instead of open.

Author: ArildF

xml/System.ServiceModel/ICommunicationObject.xml

@@ -242,7 +242,7 @@
         <AssemblyVersion>4.0.0.0</AssemblyVersion>
       </AssemblyInfo>
       <Docs>
-        <summary>Begins an asynchronous operation to close a communication object.</summary>
+        <summary>Begins an asynchronous operation to open a communication object.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[