[Freeciv] Ruleset corrections

[Vladimir Niksic <vniksic@xxxxxxx>]

I have updated some files regarding rulesets on certain countries.
Specifically I've made small changes on Croatian and Serbian town names,
adding diacritics on town names. It's not a big change, but it looks
nicer. It's still perfectly readable in the game itself, I've tested it
on different platforms. Where can I send this updated ruleset files?