config: don't ignore the --commit-fee option.

We did not take the value of --commit-fee into account : this removes
the unused option from lightningd and instead registers it in bcli,
where we set the actual feerate of commitment transactions. This also
corrects the documentation.

Changelog-Fixed: config: we now take the --commit-fee parameter into account.
Signed-off-by: Antoine Poinsot <darosior@protonmail.com>

wallet/test/test_utils.c

@@ -10,7 +10,6 @@ const struct config test_config = {
 	.anchor_confirms = 1,
 	.commitment_fee_min_percent = 0,
 	.commitment_fee_max_percent = 0,
-	.commitment_fee_percent = 500,
 	.cltv_expiry_delta = 6,
 	.cltv_final = 10,
 	.commit_time_ms = 10,