style(9): Note larger divergence than implied

Times have changed, and we've diverged somewhat from the original style
guide, while still keeping much of the flavor and flair of its spirit as
the C language has evolved over the last 30 years since 4.4 was
released.

Sponsored by: Netflix

(cherry picked from commit a26b96a930da44bbc0cc28e5764b9b6a2cf5b352)