NIP-24 ใฎ kind 0 ใฎ extra field ใซไปฅไธใ่ถณใใใจๆใใใงใใใฉใใงใใใ๏ผ
- `language`: a string representing the author's preferred language, in the format defined by [IETF BCP 47](
Information on BCP 47 » RFC Editor
) (e.g., "en", "en-US", "es", "es-AR").