Sync SDL3 wiki -> header

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include/SDL3/SDL_gpu.h

@@ -2197,6 +2197,14 @@ extern SDL_DECLSPEC SDL_GPUSampler *SDLCALL SDL_CreateGPUSampler(
  *   [[stage_in]] attribute which will automatically use the vertex input
  *   information from the SDL_GPUGraphicsPipeline.
  *
+ * Shader semantics do not matter in D3D12 and for ease of use the SDL
+ * implementation assumes that they will all be TEXCOORD. If you are using
+ * HLSL as the shader source language, your vertex semantics should start at
+ * TEXCOORD0 and increment like so: TEXCOORD1, TEXCOORD2, etc. If you wish to
+ * change the semantic prefix to something other than TEXCOORD you can use
+ * SDL_PROP_GPU_DEVICE_CREATE_D3D12_SEMANTIC_NAME_STRING with
+ * SDL_CreateGPUDeviceWithProperties().
+ *
  * \param device a GPU Context.
  * \param createinfo a struct describing the state of the shader to create.
  * \returns a shader object on success, or NULL on failure; call