Add tooltips for voting buttons, with optional overrides

[cellio]

https://meta.codidact.com/questions/278743

The tooltips for the voting buttons currently just show the Wilson score, which is not very useful. It would be better to have some guidance for voting.

The original suggestion was for static text (along the lines of Some Other site that says something like "this is useful; it shows research effort" for upvotes). But different categories with different types of content mean one size doesn't fit all; "questions" on Code Golf are very different from conventional questions that ask for information, Software Development might want to say something about a minimum complete example, and blog posts are different from wiki pages even though they're both articles.

This request is for default text with per-category overrides. Because we don't want to have potentially six different overrides on a category (question, answer, article * up, down), and because the up and down guidance are usually just inverses of each other, I suggest one tooltip that applies to both voting buttons for reach post type, with category overrides.

Suggested defaults (copying our doc team @sarahmccuan @superplane39 for further refinement):

• Question: Upvote if the question is clear, supplies all needed information, and is interesting. Downvote for the reverse.

• Answer: Upvote if this answers the question correctly, with supporting information. Downvote if it is wrong or can't be evaluated with the information given.

• Article: Upvote if this post is interesting. Downvote if it is unclear or not helpful.

The category edit page would get three more textboxes. As with post guidance and other fields, leaving them blank means use the default, and you can override just the ones you care about.