docs: Incorrect comment for independent_bid_threshold in SubmissionConfig

I noticed a potentially misleading comment for the independent_bid_threshold field within the SubmissionConfig struct in crates/rbuilder/src/live_builder/block_output/relay_submit.rs.

https://github.com/flashbots/rbuilder/blob/9a4f6b60838fd871c4e4bd777307c552848e1d8f/crates/rbuilder/src/live_builder/block_output/relay_submit.rs#L107-L108

I think the comment should likely be:
/// Bids above this value will only go to **independent** relays.

This seems to be a minor documentation discrepancy. Clarifying this would help users better understand the configuration and its behavior.
Thanks!