Edit: Not a real series. There’s just the one story in Watchmen and an adaptation of that.
Tales of the Black Freighter is a swashbuckler anthology pirate comic book series. It was published by National Comics (which later became DC Comics).
Shying away from mainstream adventures, Tales of the Black Freighter’s radical and innovative stories show a disturbing reality against metaphysical terrors and perverse comments on the human condition.
No it’s not, that wiki is all in-universe Watchmen lore and because it makes references to real world stuff that exists in the Watchmen universe, like EC and DC comics, it sounds like it is talking about the real world, but it isn’t. I think OP got confused by that.