[Docs] Convert rST to MyST (Markdown) (#11145)

Signed-off-by: Rafael Vasquez <rafvasq21@gmail.com>

docs/source/design/input_processing/input_processing_pipeline.md

@@ -0,0 +1,19 @@
+(input-processing-pipeline)=
+
+# Input Processing Pipeline
+
+1. Input data is passed to {class}`~vllm.LLMEngine` (or {class}`~vllm.AsyncLLMEngine`).
+
+2. Tokenize the data if necessary.
+
+3. Process the inputs using {meth}`INPUT_REGISTRY.process_input <vllm.inputs.registry.InputRegistry.process_input>`.
+
+   - For example, add placeholder tokens to reserve KV cache for multi-modal embeddings.
+
+4. Send the processed inputs to {class}`~vllm.executor.executor_base.ExecutorBase`.
+
+5. Distribute the inputs via {class}`~vllm.worker.worker_base.WorkerBase` to {class}`~vllm.worker.model_runner_base.ModelRunnerBase`.
+
+6. If the data contains multi-modal data, convert it into keyword arguments using {meth}`MULTIMODAL_REGISTRY.map_input <vllm.multimodal.MultiModalRegistry.map_input>`.
+
+   - For example, convert a {class}`PIL.Image.Image` input to its pixel values for a vision model.