Guidelines? You've linked to privileges. Assumed you mean "What is voting down?" which states:
Voting down, also known as "casting downvotes", is how the community
indicates which questions and answers are least useful. When should I
Use your downvotes whenever you encounter an egregiously sloppy,
no-effort-expended post, or an answer that is clearly and perhaps
You have a limited number of votes per day, and answer down-votes cost
you a tiny bit of reputation on top of that; use them wisely.
Now I've personally tried to encourage leaving comments when you downvote - we have a featured meta post on this very topic. Anyone reading this answer - PLEASE go read that post.
What you may find is that since the guidelines state that it is "how the community indicates it's a least useful question, sloppy, not useful, or incorrect" - that they feel it's enough to vote as it indicates that.
However, as you've shown, it's not enough. How does a new person know what they're doing is wrong? How do they learn? How do you get to find out if your constructed answer is incorrect or just considered sloppy? This is where leaving comments comes in, despite the guidelines saying it's an option you could do instead of downvoting, I feel it's almost more important than downvoting.
The rules as you've asked for them, are simply those in the guidelines really. And there are a few other meta posts about people revenge downvoting and all that immature stuff - if it gets picked up by the automated systems, the mods can take action. But really if we want to be a productive and positive community, comments are the way to go.
So, long story short, I feel for you - everyone gets downvotes eventually without reason. It sucks, but you learn to live with it.
Now why did you get some? I can only suspect that it's because your question was really open ended. This is a Q/A site where you're asking for specific answers, not a discussion forum soliciting discussion. There's no way to definitively answer your question.
As one of the comments pointed out (yay a comment!) it'd have been better to reword it as "Is there a wiki or similar for finding quotes on travel". That can be definitively answered by someone providing Wikiquote.org, for example.
However, my view is I'd still prefer to close-vote on a question like that, rather than downvote. Save downvotes for the really bad questions, the offensive questions and the like, and still leave comments. But that's my view :/