Adding the actual command to build the image and adding a tag, so the output of docker images is the same as the one in the lab

Author: fabianenardon

developer-tools/java/chapters/ch03-build-image.adoc

@@ -41,7 +41,11 @@ CMD ["/bin/echo", "hello world"]
 
 This image uses `ubuntu` as the base image. `CMD` command defines the command that needs to run. It provides a different entry point of `/bin/echo` and gives the argument "`hello world`".
 
-Build the image:
+Build the image using the command:
+
+  docker image build . -t helloworld
+
+`.` in this command is the context for `docker image build`. `-t` adds a tag to the image.
 
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@@ -63,8 +67,6 @@ Removing intermediate container 7615d69d04ec
 Successfully built 61edf15e4cec
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-`.` in this command is the context for `docker build`.
-
 List the images available using `docker image ls`:
 
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