Update ExchangeContext::SetResponseTimeout documentation

Function description didn't provide details on what happens if you pass
in 0.

src/messaging/ExchangeContext.h

@@ -183,6 +183,10 @@ class DLL_EXPORT ExchangeContext : public ReliableMessageContext,
     // Set the response timeout for the exchange context, regardless of the underlying session type. Using
     // UseSuggestedResponseTimeout to set a timeout based on the type of the session and the application processing time instead of
     // using this function is recommended.
+    //
+    // If a timeout of 0 is provided, it implies no response is expected. Consequently, ExchangeDelegate::OnResponseTimeout will not
+    // be called.
+    //
     void SetResponseTimeout(Timeout timeout);
 
     // This API is used by commands that need to shut down all existing