chore: import upstream snapshot with attribution

doc/tutorials/gpu/table_of_content_gpu.markdown

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+@cond CUDA_MODULES
+GPU-Accelerated Computer Vision (cuda module) {#tutorial_table_of_content_gpu}
+=============================================
+
+Squeeze out every little computation power from your system by using the power of your video card to
+run the OpenCV algorithms.
+
+-   @subpage tutorial_gpu_basics_similarity
+
+    *Languages:* C++
+
+    *Compatibility:* \> OpenCV 2.0
+
+    *Author:* Bernát Gábor
+
+    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 tutorial_video_input_psnr_ssim to the GPU.
+
+-   @subpage tutorial_gpu_thrust_interop
+
+    *Languages:* C++
+
+    *Compatibility:* \>= OpenCV 3.0
+
+    This tutorial will show you how to wrap a GpuMat into a thrust iterator in order to be able to
+    use the functions in the thrust library.
+@endcond