Add Spanish, Argentina, ISO 639-1 Code: es-AR

[SergeCroise]

• update crowdin.yml (todo)
• grant access to es-AR in Crowdin (translator and proofreader)
• update mkdocs.yml (todo)
• translate e.g.: https://crowdin.com/editor/rockydocs/672/en-esar

see also https://crowdin.com/project/rockydocs

[sspencerwire]

@SergeCroise I'm going to close this one too, since it isn't possible in material-mkdocs... thank you!

[SergeCroise]

https://squidfunk.github.io/mkdocs-material/setup/changing-the-language/