Document `--bonsai-parallel-tx-processing-enabled`

[bgravenorst]

Update: https://besu.hyperledger.org/public-networks/concepts/parallel-transaction-execution

And add the CLI option:
--bonsai-parallel-tx-processing-enabled=
Enables parallelization of transactions to
optimize processing speed by concurrently
loading and executing necessary data in advance.
Will be ignored if --data-storage-format is not
bonsai (default: true)