[Doc] Add runtime demo in quick_start (#524)

* add paddle_trt in benchmark

* update benchmark in device

* update benchmark

* update result doc

* fixed for CI

* update python api_docs

* update index.rst

* add runtime cpp examples

* deal with comments

* Update infer_paddle_tensorrt.py

* Add runtime quick start

* deal with comments

Co-authored-by: Jason <928090362@qq.com>

docs/cn/quick_start/runtime/python.md

@@ -1 +1,52 @@
 # Python推理
+
+确认开发环境已安装FastDeploy，参考[FastDeploy安装](../../build_and_install/)安装预编译的FastDeploy，或根据自己需求进行编译安装。
+
+本文档以 PaddleClas 分类模型 MobileNetV2 为例展示CPU上的推理示例
+
+## 1. 获取模型
+
+``` python
+import fastdeploy as fd
+
+model_url = "https://bj.bcebos.com/fastdeploy/models/mobilenetv2.tgz"
+fd.download_and_decompress(model_url, path=".")
+```
+
+## 2. 配置后端
+
+- 更多后端的示例可参考[examples/runtime](https://github.com/PaddlePaddle/FastDeploy/tree/develop/examples/runtime)
+
+``` python
+option = fd.RuntimeOption()
+
+option.set_model_path("mobilenetv2/inference.pdmodel",
+                      "mobilenetv2/inference.pdiparams")
+
+# **** CPU 配置 ****
+option.use_cpu()
+option.use_ort_backend()
+option.set_cpu_thread_num(12)
+
+# 初始化构造runtime
+runtime = fd.Runtime(option)
+
+# 获取模型输入名
+input_name = runtime.get_input_info(0).name
+
+# 构造随机数据进行推理
+results = runtime.infer({
+    input_name: np.random.rand(1, 3, 224, 224).astype("float32")
+})
+
+print(results[0].shape)
+```
+加载完成，会输出提示如下，说明初始化的后端，以及运行的硬件设备
+```
+[INFO] fastdeploy/fastdeploy_runtime.cc(283)::Init	Runtime initialized with Backend::OrtBackend in device Device::CPU.
+```
+
+## 其它文档
+
+- [不同后端Runtime demo示例](../../../../examples/runtime/README.md)
+- [切换模型推理的硬件和后端](../../faq/how_to_change_backend.md)