Add "text" content-hint value

Fixes #23

index.html

@@ -170,7 +170,8 @@ <h2>Extension to MediaStreamTrack</h2>
       <li>
         If this <a>MediaStreamTrack</a>'s <a>kind</a> attribute is
         <code>"video"</code>, and <i>value</i> is not one of <code>""</code>,
-        <code>"motion"</code>, or <code>"detail"</code>, abort these steps.
+        <code>"motion"</code>, <code>"detail"</code> or <code>"text"</code>,
+        abort these steps.
       </li>
       <li>
         Set this <a>MediaStreamTrack</a>'s application-set content hint to
@@ -246,6 +247,18 @@ <h3>Video Content Hints</h3>
         Artefacts from quantization or downscaling that make small text or line
         art unintelligible should be avoided.
       </p></td></tr>
+      <tr><td><code id="idl-def-VideoContentHint.detail">text</code></td><td><p>
+            The track should be treated as if video details are extra important,
+            and that significant sharp edges and areas of consistent color can
+            occur frequently.
+            This is generally applicable to presentations or web pages with text
+            content. This setting would normally optimize for
+            detail in the resulting individual frames rather than smooth
+            playback, and may take advantage of encoder tools that optimize for
+            text rendering.
+            Artefacts from quantization or downscaling that make small text
+            or line art unintelligible should be avoided.
+      </p></td></tr>
     </tbody></table>
   </section>
 </body>