Please add clarification to the page "Locale codes"

**Your Godot version:**

Documentation for godot 4.2

**Issue description:**

The helpful page on internationalization shows how to specify 'en' or 'zh' but it doesn't how how to specify, 'en_uk' or 'zh_tw', and doesn't make clear if its even possible to do this:

https://docs.godotengine.org/en/stable/tutorials/i18n/internationalizing_games.html

i.e. can we do:
en_uk: colour
en_us: color
zh_tw:顏色
zh_cn:颜色

The page above does link to this following page:

https://docs.godotengine.org/en/stable/tutorials/i18n/locales.html#doc-locales

This page does mention `language_Script_COUNTRY_VARIANT` so perhaps this suggests we can specify languages with more specificity. But it's not clear how we would do it. It is not clear to me what the four letter `script` code would be, and it does say it is optional, so can we just leave out out, is the idea that we can just say `language_COUNTRY` as we would in other programming languages and web servers?

I propose the page on internationalizing games include a few more specific examples that demonstrate how to specify more precisely if the interface is traditional Chinese or simplified. (Or even US/UK/AU English).