8198793: Add launcher support for preview features

Reviewed-by: mchung, sundar

src/java.base/share/classes/sun/launcher/resources/launcher.properties

@@ -113,6 +113,8 @@ java.launcher.opt.footer = \
 \                  one or more argument files containing options\n\
 \    -disable-@files\n\
 \                  prevent further argument file expansion\n\
+\    --enable-preview\n\
+\                  allow classes to depend on preview features of this release
 \To specify an argument for a long option, you can use --<name>=<value> or\n\
 \--<name> <value>.\n