Copy documentation to functions generated by #[derive(WrapperApi)]

[OpenByteDev]

If possible #[derive(WrapperApi)] should copy the documentation from the corresponding field to the generated method. An example of this not happening can be seen here:

• Documentation: https://docs.rs/netcorehost/0.2.2/netcorehost/bindings/hostfxr/struct.HostfxrLib.html
• Source: https://docs.rs/netcorehost/0.2.2/src/netcorehost/bindings/hostfxr.rs.html#47-322

[OpenByteDev]

I implemented this in a fork for anyone that needs it.