Document System.Diagnostics.Tracing.EventCounter.Dispose (#3453)

Author: carlossanlop

xml/System.Diagnostics.Tracing/EventCounter.xml

@@ -109,7 +109,7 @@ For an example of how to use the <xref:System.Diagnostics.Tracing.EventCounter>
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Releases the resources used by the current instance of the <see cref="T:System.Diagnostics.Tracing.EventCounter" /> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>