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.

https://github.com/1Password/typeshare/blob/a03f5ef506a8cf24e497a6a1f4a3c7d87ae2844d/core/src/language/kotlin.rs#L401