[ja] Translate content/en/docs/concepts/architecture/mixed-version-proxy.md into Japanese

[pratik-mahalle]

This is a Feature Request

What would you like to be added

Translate content/en/docs/concepts/architecture/mixed-version-proxy.md into Japanese

Website Link

• English: https://kubernetes.io/docs/concepts/architecture/mixed-version-proxy/

Why is this needed

This page is not translated yet.

/area localization /language ja /assign

[kfess]

/triage accepted