Adding CUDA materials (Programming and best practice guides) (#3082)

* Adding Cuda PDFs

* putting alphabetically order

* removed extra space

Always check the output of the linter!

free-programming-books.md

@@ -1066,6 +1066,8 @@ Kerridge (PDF) (email address *requested*, not required)
 
 ### CUDA
 
+* [CUDA C Best Practices Guide](https://docs.nvidia.com/pdf/CUDA_C_Best_Practices_Guide.pdf) (PDF)
+* [CUDA C Programming Guide](https://docs.nvidia.com/pdf/CUDA_C_Programming_Guide.pdf) (PDF)
 * [OpenCL Programming Guide for CUDA Architecture](http://www.nvidia.com/content/cudazone/download/OpenCL/NVIDIA_OpenCL_ProgrammingGuide.pdf) (PDF)