It's better add comments on param BlockBatchLimit

[tmors]

💎 Issue

Background

When i upgraded my Goerli beacon-chain, i found that i couldn't sync blocks . I enabled debug then i got an error msg that "Request exceeded max size 128".
After that I read the source code and found that the MaxRequestBlock is modified (from 1024 to 128), So BlockBatchLimit is changed (1024 is not supported)

func MaxRequestBlock(e primitives.Epoch) uint64 {
	if e >= BeaconConfig().DenebForkEpoch {
		return BeaconConfig().MaxRequestBlocksDeneb // 128 
	}
	return BeaconConfig().MaxRequestBlocks // 1024
}

, but I still use the parameters(--BlockBatchLimit 1024) as before. So i think a comment is necessary to remind that the maximum of the param

Context and background information on the discussion...

Description

	// BlockBatchLimit specifies the requested block batch size.
	BlockBatchLimit = &cli.IntFlag{
		Name:  "block-batch-limit",
		Usage: "The amount of blocks the local peer is bounded to request and respond to in a batch. **Maximum 128**",
		Value: 64,
	}

Just like above bold comments (Maximum 128) to remind the range of it.