Added the "Similarity check (PNSR and SSIM) on the GPU" tutorial. Corrected an highgui TOC tree mistake.

doc/tutorials/gpu/table_of_content_gpu/table_of_content_gpu.rst

@@ -1,12 +1,36 @@
 .. _Table-Of-Content-GPU:
 
 *gpu* module. GPU-Accelerated Computer Vision
------------------------------------------------------------
+---------------------------------------------
 
 Squeeze out every little computation power from your system by using the power of your video card to run the OpenCV algorithms.
 
-.. include:: ../../definitions/noContent.rst
+.. include:: ../../definitions/tocDefinitions.rst
+
++ 
+  .. tabularcolumns:: m{100pt} m{300pt}
+  .. cssclass:: toctableopencv
+
+  =============== ======================================================
+  |hVideoWrite|   *Title:* :ref:`gpuBasicsSimilarity`
+
+                  *Compatibility:* > OpenCV 2.0
+
+                  *Author:* |Author_BernatG|
+
+                  This will give a good grasp on how to approach coding on the GPU module, once you already know how to handle the other modules. As a test case it will port the similarity methods from the tutorial :ref:`videoInputPSNRMSSIM` to the GPU. 
+
+  =============== ======================================================
+
+  .. |hVideoWrite| image:: images/gpu-basics-similarity.png
+                   :height: 90pt
+                   :width:  90pt
 
 .. raw:: latex
 
    \pagebreak
+
+.. toctree::
+   :hidden:
+
+   ../gpu-basics-similarity/gpu-basics-similarity