Document `--cache-last-block-headers`

[alexandratran]

Document new config option --cache-last-block-headers to store the last block headers from the blocks persisted to the blockchain. See besu-eth/besu#9223 for more information.

[m4sterbunny]

Adding issue #1853 to this issue to do both items together.

Note besu-eth/besu#9248 seems to have mismatch between the PR description and the code in the PR.

• PR description: “new flag --preload-block-headers-cache-enabled”
• Code in the same PR names = {"--cache-last-block-headers-preload-enabled"}