doc: Missing version info for `TextEncoder.prototype.encodeInto()`

[skyclouds2001]

Affected URL(s)

https://nodejs.org/docs/latest/api/util.html

Description of the problem

per #29524 and https://nodejs.org/en/blog/release/v12.11.0/, it shipped in v12.11.0/, but currently not documented (if inherit from the interface, it'll be v8.3.0, which is not true)

also, there is a version mismatch for TextDecoder, the v11.0.0 The class is now available on the global object. item should add on the interface, not the constructor

also see #13644 and https://nodejs.org/en/blog/release/v8.3.0/ for the API's initial implement

target links:
https://nodejs.org/docs/latest/api/util.html#class-utiltextdecoder
https://nodejs.org/docs/latest/api/util.html#class-utiltextencoder