Add subsection explaining the Block Deduplicator step of the Optimizer

[matheusaaguiar]

Page

Opcode-based Optimizer Section of the documentation.

https://docs.soliditylang.org/en/v0.8.23/internals/optimizer.html#opcode-based-optimizer-module

Abstract

Requested here: https://github.com/ethereum/solidity-website/pull/57#discussion_r1384926540 The block deduplicator is not covered by the documentation and a subsection explaining it is needed.