Fix base image creation example commands (#1409)

Example commands for creating a base image do not work due to multiple issues.
- 16:04 not a valid tag for ubuntu image
- apt-get install fails without preceeding `apt-get update`
- gcc command fails without `-nostartfiles` flag
- `docker run` without the `--rm` leaves behind containers which is unintuitive, and inconsistent with the build image used above.

engine/userguide/eng-image/baseimages.md

@@ -60,11 +60,11 @@ Assuming you built the "hello" executable example [from the Docker GitHub exampl
 NOTE: Because Docker for Mac and Docker for Windows use a Linux VM, you must compile this code using a Linux toolchain to end up with a Linux binary. Not to worry, you can quickly pull down a Linux image and a build environment and build within it:
 
     $ docker run --rm -it -v $PWD:/build ubuntu:16.04
-    container# apt-get install build-essential
+    container# apt-get update && apt-get install build-essential
     container# cd /build
-    container# gcc -o hello -static hello.c
+    container# gcc -o hello -static -nostartfiles hello.c
 
-Then you can run it (on Linux, Mac, or Windows) using: `docker run hello`
+Then you can run it (on Linux, Mac, or Windows) using: `docker run --rm hello`
 
 This example creates the hello-world image used in the tutorials.
 If you want to test it out, you can clone [the image repo](https://github.com/docker-library/hello-world)