Updated README to use the docker container with a host mount. fixes 2 (…

…#3)

* Updated README to use the docker container with a host mount.

* Update README.md

README.md

@@ -12,11 +12,21 @@ npm install && npm start
 ```
 
 ### As a docker image
+#### Basic
 ```
 docker build -t <your username>/ytdl-webserver .
 docker run -p 3000:3000 -d <your username>/ytdl-webserver
 ```
 
+#### Advanced
+Build the docker image, create a directory to hold and access the downloaded videos on the host, and then start a container instance of the image.  
+```
+docker build -t <your username>/ytdl-webserver .
+mkdir /tmp/videos
+docker run -v /tmp/videos:/home/app/public/temp -p 3000:3000 -d <your username>/ytdl-webserver
+```
+In the example above, we are creating a directory under /tmp to hold the videos and then specifying a host mount to the container that corresponds to that new directory.  You may update this to any path on your host or use a different existing path if you would prefer. The host mount also improves performance as the downloaded files are written to the native host filesystem bypassing the CoW filesystem of the container.
+
 
 ## Development
 To start contributing you only have to run one command.