Documentation from objects not shown in completion window

[chibby0ne]

When trying to use deoplete-rust autocompletion on an object I can see the list of attributes and methods in a drop down selection but going through that drop down selection does not show the comments/documentation about that attribute/method only that method's signature, in the way you can in other languages.

Here's an asciinema example of what I get using a default configuration (setting the required variables) with deoplete-rust in the case of a simple Vec.
https://asciinema.org/a/4W973QDH549qN1RyGVsPwY0rw

I'm wondering if it's possible to show something like in the case of Python with deoplete-jedi, where going through the selection shown you can see the complete docstring in addition to the method's signature:
https://asciinema.org/a/hiWC2Yg6DwF32gFWbRmQPVelL

I'm running latest master as of today, commit ID: 0a86e50, with neovim v.0.3.1

Having the documentation associated with a method/function is very helpful and pretty fundamental, since most completion engines normally show this information in IDE environments.