What does " or so the story went", at the end of a sentence mean?

Question

I was reading a novel in which there was this sentence regarding two friends(both girls). The sentence was,
They decided to go together so that one could keep a lookout while the other bathed, "or so the story went".
What do the last words mean?

Answer 1

It means that's how it was described or explained and has the implication there may have been another reason that is either unspecified or being withheld.

Answer 2

That is the story as I heard it. I am not claiming it is true. Just how I heard it. It might seem unlikely, but it is still what "they" say actually happened. I wasn't there so I don't know, but this is what people say. Just telling you what I heard, not what I believe or think.

Answer 3

That is what some people said, but it is not definitely true, and quite probably I do not believe it.

Answer 4

That this was what the story said, but it may not be true.