Tools: setup-unit: -hh: The advanced commands aren't experimental

I've been using them for a long time, and they are quite useful and
stable.  Let's say they're advanced instead of experimental.

Reviewed-by: Andrew Clayton <a.clayton@nginx.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

tools/setup-unit

@@ -63,8 +63,7 @@ OPTIONS
                 Print this help.
 
         --help-more
-                Print help for more commands.  They are experimental.  Using
-                these isn't recommended, unless you know what you're doing.
+                Print help for more (advanced) commands.
 
 __EOF__
 }