docs: change gossip rpc return to accepted count instead of offered count

[KolbyML]

Currently portal_historyGossip returns the amount of nodes we offered the content to but this metric isn't very useful as for all we know the nodes it offered the content to could be dead or even worse didn't accept the content in the first place.

That is why I propose we switch portal_historyGossip to return the amount of nodes that accepted the content instead. This idea was taken from Jason Carver in Trin chat on the Portal Discord. I ended up implementing it on Trin and it was 1000 times easier to know what was going on where before I would see a number 8 half sometimes the content would be accepted by 0 nodes and then it was hard to even know if gossip did anything.

If portal_historyGossip gossip's to 8 nodes and 0 nodes accept the content. At that point it doesn't matter if portal_historyGossip returns 8 or 8000 the number doesn't say anything if none accepted it.

[KolbyML]

@kdeme @carver @pipermerriam ping for review

[pipermerriam]

Is this still relevant? What should happen here?

[KolbyML]

No i will close it

[KolbyML]

We have trace_gossip in trin but I don't think all clients should be required to implement it