docs: fix code block formatting in gpu-sampling.md

Author: danbev

notes/llama.cpp/gpu-sampling.md

@@ -95,7 +95,6 @@ the graph with the operations they need to perform.
 To be able to perform the GPU sampling operations on the GPU this will be done
 in a similar manner to how pooling is currently applied. To enable this a
 llama_sampler has been added to llama_context_params:
-```c++
 ```c++
         struct llama_sampler_chain_params gpu_sampler_params = llama_sampler_chain_default_params();
         struct llama_sampler * gpu_sampler_chain = llama_sampler_chain_init(gpu_sampler_params);