Made "Grouping property values" into a section so that it can be linked from elsewhere.

Added a "card flip" example for background-visibility
Rewrote the "Accumulated 3D Transformation Matrix Computation" section.
Other minor tweaks.

Author: smfr

css-transforms/ChangeLog

@@ -1,3 +1,9 @@
+2014-10-25 Simon Fraser <simon.fraser@apple.com>
+    Made "Grouping property values" into a section so that it can be linked from elsewhere.
+    Added a "card flip" example for background-visibility
+    Rewrote the "Accumulated 3D Transformation Matrix Computation" section.
+    Other minor tweaks.
+
 2014-10-24 Simon Fraser <simon.fraser@apple.com>
     Rewrite the "Transform Rendering Model" section with a more precise description of the model. Substantive changes include a new 'auto' value for transform-style, the concept of a "3D-rendering context" (akin to CSS stacking context), and a better description of the rendering order.