[api] Improve documentation for SetNamedPropertyHandler().

BUG=v8:5260

Review-Url: https://codereview.chromium.org/2268673002
Cr-Commit-Position: refs/heads/master@{#38823}

include/v8.h

@@ -4756,8 +4756,10 @@ class V8_EXPORT ObjectTemplate : public Template {
    * from this object template, the provided callback is invoked instead of
    * accessing the property directly on the JavaScript object.
    *
-   * Note that new code should use the second version that can intercept
-   * symbol-named properties as well as string-named properties.
+   * SetNamedPropertyHandler() is different from SetHandler(), in
+   * that the latter can intercept symbol-named properties as well as
+   * string-named properties when called with a
+   * NamedPropertyHandlerConfiguration. New code should use SetHandler().
    *
    * \param getter The callback to invoke when getting a property.
    * \param setter The callback to invoke when setting a property.