8320788: The system properties page is missing some properties

Reviewed-by: rriggs, iris
Backport-of: 3bd9042054116365323912ed5867b70936fe85c4

Author: naotoj

src/java.base/share/classes/java/lang/System.java

@@ -57,6 +57,7 @@
 import java.security.ProtectionDomain;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Properties;
@@ -813,6 +814,10 @@ public static native void arraycopy(Object src,  int  srcPos,
      * Note that even if the security manager does not permit the
      * {@code getProperties} operation, it may choose to permit the
      * {@link #getProperty(String)} operation.
+     * <p>
+     * Additional locale-related system properties defined by the
+     * {@link Locale##default_locale Default Locale} section in the {@code Locale}
+     * class description may also be obtained with this method.
      *
      * @apiNote
      * <strong>Changing a standard system property may have unpredictable results