Document guidelines for every field

[axelboc]

With all the discussions that took place over the past few months, I thought it wise to add to the content guidelines for each field in CONTRIBUTING.md.

I wrote as much as I could, trying to remember all the decisions that we've made so far. I'm sure I've made a lot of mistakes and forgot some things. Please pick them apart 🔍 and don't hesitate to crush my feelings if you think something could be better written! ❤️

There's probably a bit of work to be done to apply these guidelines consistently in the deck (notably for capitals), and they'll probably have to be adjusted as we go. I'm still not a huge fan of having multiple capitals in the Capital field, so I'm down with any guideline we can write to avoid that... 😂

[aplaice]

That's really clear and thorough, while still being maximally concise!

Should the case of duplicate country names (#212) — currently only Saint-Martin/Sint Maarten in French and Spanish be mentioned or is it too much of a tiny corner-case?

(I can't really think of any other potential omissions.)

[aplaice]

Shouldn't this:

In the very unlikely case that two countries share the same name in a given language,

be at the end of line 65, giving something like:

If the title of the Wikipedia article contains a parenthetical portion for disambiguation purposes, it must be removed, unless the disambiguation is needed in the deck — e.g. Saint-Martin (Antilles françaises) and Saint-Martin (royaume des Pays-Bas) in the French deck — in the very unlikely case that two countries share the same name in a given language.

[axelboc]

Woops, thanks! I simplified the paragraph a little (I think).

[ohare93]

Scraped the bottom of the barrel in terms of review comments 😅 Looks good 👍