impl AsRef for Gd<T>

[ColinWttt]

issue:#1086

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-1087

[Bromeon]

Thanks! Discussion in #1086.

For the future, when you want to open a PR and issue at the same time, you can also write the problem statement directly in the PR. Unlike Godot, we don't have a "every change needs an issue" policy, and then discussion also remains in one place 🙂