chore: import upstream snapshot with attribution

docs/serving/online_serving/renderer.md

@@ -0,0 +1,14 @@
+# Renderer APIs
+
+Our renderer API is designed to disaggregate the render phase(preprocessing) and enable a token-in / token-out API server.
+
+- GPU-less deployment of frontend: Allow preprocessing (tokenization, MM input processing) and postprocessing (detokenization, tool call parsing, reasoning parsing) to run without GPU.
+- Disaggregated tokenization: Support use cases such as llm-d, Dynamo, and custom frontends that need to leverage vLLM's preprocessing logic without running the full inference engine.
+- Tokens-in / tokens-out engine: Make the engine a pure token-in / token-out service, decoupled from request preprocessing.
+
+## API Reference
+
+- [Completions Render API](renderer.md) (`/v1/completions/render`)
+    - Render completion requests
+- [Chat Completions Render API](renderer.md) (`/v1/chat/completions/render`)
+    - Render chat completions