New docs: `pertxgaslimit` genesis config for BFT networks

[alexandratran]

What docs should be added?

What changed: Besu now supports an opt-in genesis config field pertxgaslimit (under config.qbft and config.ibft2), which overrides the EIP-7825 default per-transaction gas cap (2^24) for private/free-gas BFT networks. Behavior: field absent -> EIP-7825 default applies; 0 -> cap disabled (only block gas limit applies); N > 0 -> cap at N gas (must be <= configured block gas limit, validated at startup). The field also supports fork transitions via the existing transitions.qbft/transitions.ibft2 array, matching the pattern used for blockperiodseconds.

Content type

• Concept
• How-to guide
• Get-started or onboarding
• Reference
• Tutorial

Location

• docs/private-networks/how-to/configure/consensus/qbft.md - add pertxgaslimit to the Genesis file options table, next to blockperiodseconds/epochlength, including the transitions example.
• docs/private-networks/how-to/configure/consensus/ibft.md - same addition for IBFT2.

Source links

besu-eth/besu#10722