Bump A-Frame documentation (aframevr/aframe@c0d279f...4a4e6bd).

Author: SupermediumBot

docs/master/primitives/a-image.html

@@ -1125,7 +1125,7 @@ <h2 id="attributes"><a href="#attributes" class="headerlink" title="Attributes">
 <tr>
 <td>transparent</td>
 <td>material.transparent</td>
-<td>false</td>
+<td>true</td>
 </tr>
 <tr>
 <td>width</td>