Add "libraries" to General Overview

[spudthebud]

I'm commenting on "Accessibility Metadata Display Guide for Digital Publications 2.0"

I'm commenting on the General Overview section

This document targets implementers such as bookstores, retailers, distributors etc.

I suggest adding libraries.

[avneeshsingh]

These guidelines are useful for libraries. So, this looks appropriate.
A topic for next editors' call.

[GeorgeKerscher]

I think this is an easy decision. I was just going to add it.