Documentation of libraries in the Editor

A way to be able to show documentation for also libraries, and improve usability as that documentation appears to the user would be interesting.

Could appear when the user holds CTRL upon the name (as in the image attached).

Or could come along with autocomplete (#849)

Start by reviewing the Editor's existing handling of library names and the autocomplete work referenced in #849. Compare the proposed CTRL-on-name interaction with showing documentation alongside autocomplete, then clarify the source of library documentation and the expected user-facing behavior before implementation.

Written by the indexing model from the issue text.