Kotlin doc comments should follow kotlin style

[demosdemon]

See https://kotlinlang.org/docs/coding-conventions.html#documentation-comments

Currently, the Kotlin generator writes doc comments in the same style as rust (with the ///) which is not parsed as a doc comments in Kotlin.

typeshare/core/src/language/kotlin.rs

Line 401 in a03f5ef

writeln!(w, "{}/// {}", "\t".repeat(indent), comment)?;