Better language code reference

[akhyarrh]

On sitepoint's ISO 2 Letter Language Codes (linked on html-lang section), language code for Indonesian are IN, but HTML validator said to use ID instead as IN are deprecated.

Here's registry from https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry

Type: language
Subtag: in
Description: Indonesian
Added: 2005-10-16
Deprecated: 1989-01-01
Preferred-Value: id
Suppress-Script: Latn
Macrolanguage: ms

scrot from https://r12a.github.io/apps/subtags/

So, change it to updated reference to help user avoid validation error

Sorry for my bad english
Thanks