Update README.md (#946)

Update README.md

README.md

@@ -43,10 +43,23 @@ Developers on a OS for which there is no binary package, or who would like to st
 1. Install [Docker](https://www.docker.com/).
 1. Check out the foundationdb repo.
 1. Build Linux docker image using the file `Dockerfile` located in the `build` source directory.
+
+    ```shell
+    cd /dir/path/foundationdb
+    docker build ./build -t <image-tag-name>
+    ```
+
 1. Run the docker image interactively [Docker Run](https://docs.docker.com/engine/reference/run/#general-form) with the directory containing the foundationdb repo mounted [Docker Mounts](https://docs.docker.com/storage/volumes/).
-`docker run -it -v '/local/dir/path/foundationdb:/docker/dir/path/foundationdb' /bin/bash`
-1. Navigate to the mounted directory containing the foundationdb repo.
-`cd /docker/dir/path/foundationdb`
+
+    ```shell
+    docker run -it -v '/local/dir/path/foundationdb:/docker/dir/path/foundationdb' <image-tag-name> /bin/bash
+    ```
+
+1. Navigate to the container's mounted directory which contains the foundationdb repo.
+
+    ```shell
+    cd /docker/dir/path/foundationdb
+    ```
 1. Run `make`.
 
 This will build the fdbserver binary and the python bindings. If you want to build our other bindings, you will need to install a runtime for the language whose binding you want to build. Each binding has an `.mk` file which provides specific targets for that binding.