Updated instructions to include docker pull before running the commands

README.md

@@ -4,14 +4,49 @@ For running the [Softcover](https://github.com/softcover/softcover) eBook typese
 
 Image hosted on [DockerHub](https://hub.docker.com/r/softcover/softcover).
 
-## Usage:
+
+## Usage
+
+The first step is to download the docker image using the commend:
+```bash
+docker pull softcover/softcover
+```
+Note this step takes a long time since we it downloads more than 3GB of files
+(a complete LaTeX distribution, Inkscape, and a complete Ruby dev environment).
+
 
 Build html from book directory:
 ```bash
-docker run -v `pwd`:/book softcover:latest sc build:html
+docker run -v `pwd`:/book softcover/softcover:latest sc build:html
+```
+
+Run softcover interactive server:
+```bash
+docker run -v `pwd`:/book -d -p 4000:4000 softcover/softcover:latest sc server
+```
+then open the URL http://localhost:4000/your-book-name.html in your browser.
+
+
+
+## Interactive shell
+
+To run bash inside the container use the following command:
+```bash
+docker run -ti -v `pwd`:/book -p 4000:4000 softcover/softcover:latest /bin/bash
 ```
+The current working directory is mounted as `/book`.
 
-Run server:
+
+
+## Local docker image build
+
+As an alternative to `docker pull` command above, you can build the docker image
+locally from the provided `Dockerfile`. To build the docker image, run the command
 ```bash
-docker run -v `pwd`:/book -d -p 4000:4000 softcover:latest sc server
+docker build -t softcover .
 ```
+This step takes a fairly long time since it downloads a complete TeX distribution
+and other system packages required to run Softcover. Time to go get lunch!
+
+After the docker build step is done, you can run all the commands shown above,
+by replacing the argument `softcover/softcover:latest` with `softcover` (local tag).