And remove deprecated autocleaninvoice docs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: Plugins: `autoclean-status` command to see what autoclean is doing.
Changelog-Deprecated: JSON-RPC: `autocleaninvoice` (use option `autoclean-expiredinvoices-age`)
Rusty Russell