Introducing WCAG 3 Explainer document

We received comments on the WCAG3 First Public Working Draft (FPWD) 
asking to move some of the introductory material to another document and 
make the guidelines more prominent and easier to find.  We have created 
an Explainer document for WCAG3 trying to follow the guidance for 
Explainers set by the W3C Technical Architecture Group (TAG).

The Explainer content is a direct move of text from the WCAG3 FPWD into 
the Explainer or it is information taken from the WCAG3 Requirements and 
early Silver published reports. It is organized to meet TAG 
recommendations for Explainers.

The Explainer is intended to be a Note. There is no normative content in 
the Explainer.

We would like to publish the Explainer with the WCAG3 heartbeat 
publication in May. It will be on survey next week, but we wanted to 
introduce it.

WCAG3 Revision (Github branch) 
<https://raw.githack.com/w3c/silver/explainer/guidelines/>

WCAG3 Explainer (Github branch)
<https://raw.githack.com/w3c/silver/explainer/explainer/>

This is the new top level of the Table of Contents (ToC) for WCAG3:

 1. Introduction
 2. Normative requirements
 3. Guidelines
 4. Testing
 5. Scoring
 6. Conformance
 7. Glossary

The top level of the Table of Contents for WCAG3 Explainer:

 1. Introduction
 2. Background and development history
 3. Goals (from WCAG3 Requirements)
 4. Non-goals or out-of-scope (from charter and charter discussions)
 5. Explanation behind decisions (from WCAG3 FPWD)
 6. Research and input from industry leaders (from Silver Design Sprint
    report) - this will be updated to Stakeholder Feedback / Opposition
    when we finish the comments on the FPWD)