README added links to the preview images

Author: vorg

README.md

@@ -9,10 +9,10 @@ MIT, see [LICENSE.md](http://github.com/vorg/pex-experiments/blob/master/LICENSE
 
 | Screenshot  | Name |
 | ------------- | ------------- |
-| ![](blocks/screenshot.jpg)| [blocks](/blocks) - procedural geometry and SSAO |
-| ![](graph/screenshot.png)| [graph](/graph) - 2D graph drawing and editing |
-| ![](instanced-stream/screenshot.jpg)| [instanced-stream](/instanced-stream) - instancing with shadows |
-| ![](shadows/screenshot.jpg)| [shadows](/shadows) - soft shadow maps|
-| ![](d3-scale-gradient/screenshot.jpg)| [d3-scale-gradient](/d3-scale-gradient) testing build-in gradients from d3|
-| ![](gradient-gamma/screenshot.jpg)| [gradient-gamma](/gradient-gamma) - gamma correction influence on color interpolation|
-| ![](benchmark/screenshot.jpg)| [benchmark](/benchmark) - simple cube benchmark|
+| [![](blocks/screenshot.jpg)](/blocks)| [blocks](/blocks) - procedural geometry and SSAO |
+| [![](graph/screenshot.png)](/graph)| [graph](/graph) - 2D graph drawing and editing |
+| [![](instanced-stream/screenshot.jpg)](/instanced-stream)| [instanced-stream](/instanced-stream) - instancing with shadows |
+| [![](shadows/screenshot.jpg)](/shadows)| [shadows](/shadows) - soft shadow maps|
+| [![](d3-scale-gradient/screenshot.jpg)](/d3-scale-gradient)| [d3-scale-gradient](/d3-scale-gradient) testing build-in gradients from d3|
+| [![](gradient-gamma/screenshot.jpg)](/gradient-gamma)| [gradient-gamma](/gradient-gamma) - gamma correction influence on color interpolation|
+| [![](benchmark/screenshot.jpg)](/benchmark)| [benchmark](/benchmark) - simple cube benchmark|