New timeline icon in tool bar

Author: dacap

tool-bar.md

@@ -6,3 +6,4 @@ The tool bar contains several tools that you can use for different purposes:
 * [Pick colors](eyedropper.md) ![Eyedropper Icon](tools/eyedropper-tool.png)
 * [Zoom](zoom.md) ![Zoom Icon](tools/zoom-tool.png)
 * [Select and transform regions](selecting.md) ![Marquee Tool Icon](tools/marquee-tool.png)
+* [Show Timeline](timeline.md) ![Timeline Icon](tools/timeline.png)