Expand Motivation and Background and clarify priorities in Scope

Fix #23

charter.html

@@ -174,6 +174,15 @@ <h1 id="title">
       </section>
       <section id=bg>
         <h2>Motivation and Background</h2>
+        <p>
+          Computer Vision enables computers to gain understanding from images
+          or videos, Natural Language Processing enables interaction between
+          computers and human languages, and Speech Recognition enables
+          computers to recognize and translate spoken language into text.
+          Bringing these experiences to the web in a privacy-preserving manner
+          requires efficient machine learning inference capabilities built into
+          the browser.
+        </p>
         <p>Enabling Machine Learning inference in
           the browser (as opposed e.g. to in the cloud) enhances privacy, since input
           data such as locally sourced images or video streams stay within the
@@ -213,6 +222,11 @@ <h2>
           and retrieve the output when hardware execution completes.
           </li>
         </ul>
+        <p>
+          This Working Group puts priority on building blocks required by
+          well-known model architectures in the fields of Computer Vision,
+          Natural Language Processing and Speech Recognition.
+        </p>
         <p>
           The APIs in scope of this group will not be tied to any particular
           platform and will be implementable on top of existing major platform