Ping - update documentation (#4333)

Co-authored-by: Jan Jahoda <[email protected]>

Author: Jan Jahoda

xml/System.Net.NetworkInformation/Ping.xml

@@ -182,7 +182,7 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Releases the unmanaged resources and disposes of the managed resources used by the <see cref="T:System.Net.NetworkInformation.Ping" />.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>