update README

Dockerfile

@@ -0,0 +1,13 @@
+FROM ubuntu:16.04
+MAINTAINER Changxu Wang <[email protected]>
+
+RUN apt-get update -y
+RUN apt-get install -y g++ cmake libboost-dev libgoogle-perftools-dev
+
+COPY . /opt/nsg
+
+WORKDIR /opt/nsg
+
+RUN mkdir -p build && cd build && \
+    cmake -DCMAKE_BUILD_TYPE=Release .. && \
+    make -j $(nproc)

README.md

@@ -103,6 +103,22 @@ $ cmake -DCMAKE_BUILD_TYPE=Release ..
 $ make -j
 ```
 
+### (Optional) Docker Usage
+
+1. Build Docker Image
+
+```shell
+$ docker build -t nsg .
+```
+
+2. Run and log into Docker container
+
+```
+$ docker run -it --name nsg nsg bash
+```
+
+> You can modify the Dockerfile under the project as you need.
+
 ## Usage
 
 The main interfaces and classes have its respective test codes under directory `tests/`