Add goals to CONTRIBUTING.md (#14)

CONTRIBUTING.md

@@ -20,6 +20,24 @@ The first step for any substantive contribution is to either:
 Issues are where individual reports and Community Group discussions come together such
 that the eventual consensus can be turned into official language.
 
+## Goals and Non-Goals
+
+The main goal of the Web Components Community Group docs-and-guides effort is to provide explanation, advocacy, and documentation of shared web components concepts in a common location that is not tied to any specific web components library.
+
+This documentation should be ideal for readers interested in learning about web components first - before thinking about libraries; and for web component libraries to reference to cover the standard web components foundations without writing it all themselves.
+
+### Goals
+* Provide a polished landing page for web components, similar in spirit to homepages for frameworks.
+* Explain what web components are and why they are useful
+* Advocate for web components in a library-neutral way
+* Document core web component technical concepts
+* Educate readers on useful library-agnostic patterns and best practices
+* Orient readers to the broader web components ecosystem, including standards work, resources, communities, libraries, tools, and components.
+
+### Non-Goals
+* Duplicate MDN references of the web components APIs
+* Document or advocate specific web components libraries
+
 ## Normative and/or substantive contributions
 
 The Web Components Community Group operates via the consensus of its membership, and discusses all significant matters prior to implementation.