options: add help to experimental_verify

Option help is required...

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/options.c b/options.c
index ed437be..16c7995 100644
--- a/options.c
+++ b/options.c
@@ -1965,6 +1965,7 @@
 		.name	= "experimental_verify",
 		.off1	= td_var_offset(experimental_verify),
 		.type	= FIO_OPT_BOOL,
+		.help	= "Enable experimental verification",
 	},
 #ifdef FIO_HAVE_TRIM
 	{