Merge pull request #38453 from stormqueen1990/update-locale-docs

[en] Document when country codes are used in the Kubernetes documentation

Author: k8s-ci-robot

content/en/docs/contribute/localization.md

@@ -39,6 +39,10 @@ standard](https://www.loc.gov/standards/iso639-2/php/code_list.php) to find your
 localization's two-letter language code. For example, the two-letter code for
 Korean is `ko`.
 
+Some languages use a lowercase version of the country code as defined by the
+ISO-3166 along with their language codes. For example, the Brazilian Portuguese
+language code is `pt-br`.
+
 ### Fork and clone the repo
 
 First, [create your own
@@ -88,6 +92,11 @@ You'll need to know the two-letter language code for your language. Consult the
 to find your localization's two-letter language code. For example, the
 two-letter code for Korean is `ko`.
 
+If the language you are starting a localization for is spoken in various places
+with significant differences between the variants, it might make sense to
+combine the lowercased ISO-3166 country code with the language two-letter code.
+For example, Brazilian Portuguese is localized as `pt-br`.
+
 When you start a new localization, you must localize all the
 [minimum required content](#minimum-required-content) before
 the Kubernetes project can publish your changes to the live