rpcn: update docs for max_message_bytes

[josephwoodward]

Update docs for max_message_bytes to highlight before compression.

[claude]

Commits
LGTM

Review
Documentation-only change clarifying that max_message_bytes is measured before compression, with an uncompressed-fallback caveat. The Go edit only touches the FranzProducerLimitsFields ConfigSpec description string, and all six generated .adoc files were regenerated to match exactly (task docs output is complete and consistent — no stale copies of the old text remain). No logic changes, so no tests required.

LGTM

[claude]

Commits
LGTM

Review
Documentation-only change: adds "measured before compression is applied" to the max_message_bytes field description in franz_writer.go, with the six .adoc files being the regenerated docs. The generated docs match the source description string exactly and consistently across all components.

LGTM