Add ability to add multiple tags with docker build

Signed-off-by: Shijiang Wei <mountkin@gmail.com>

docs/reference/builder.md

@@ -62,6 +62,11 @@ the build succeeds:
 
     $ docker build -t shykes/myapp .
 
+To tag the image into multiple repositories after the build,
+add multiple `-t` parameters when you run the `build` command:
+
+    $ docker build -t shykes/myapp:1.0.2 -t shykes/myapp:latest .
+
 The Docker daemon runs the instructions in the `Dockerfile` one-by-one,
 committing the result of each instruction
 to a new image if necessary, before finally outputting the ID of your

docs/reference/commandline/build.md

@@ -31,7 +31,7 @@ parent = "smn_cli"
       --pull=false                    Always attempt to pull a newer version of the image
       -q, --quiet=false               Suppress the verbose output generated by the containers
       --rm=true                       Remove intermediate containers after a successful build
-      -t, --tag=""                    Repository name (and optionally a tag) for the image
+      -t, --tag=[]                    Name and optionally a tag in the 'name:tag' format
       --ulimit=[]                     Ulimit options
 
 Builds Docker images from a Dockerfile and a "context". A build's context is
@@ -227,6 +227,14 @@ uploaded context. The builder reference contains detailed information on
 This will build like the previous example, but it will then tag the resulting
 image. The repository name will be `vieux/apache` and the tag will be `2.0`
 
+You can apply multiple tags to an image. For example, you can apply the `latest`
+tag to a newly built image and add another tag that references a specific
+version.
+For example, to tag an image both as `whenry/fedora-jboss:latest` and
+`whenry/fedora-jboss:v2.1`, use the following:
+
+    $ docker build -t whenry/fedora-jboss:latest -t whenry/fedora-jboss:v2.1 .
+
 ### Specify Dockerfile (-f)
 
     $ docker build -f Dockerfile.debug .

man/docker-build.1.md

@@ -16,7 +16,7 @@ docker-build - Build a new image from the source code at PATH
 [**--pull**[=*false*]]
 [**-q**|**--quiet**[=*false*]]
 [**--rm**[=*true*]]
-[**-t**|**--tag**[=*TAG*]]
+[**-t**|**--tag**[=*[]*]]
 [**-m**|**--memory**[=*MEMORY*]]
 [**--memory-swap**[=*MEMORY-SWAP*]]
 [**--cpu-period**[=*0*]]
@@ -82,7 +82,7 @@ set as the **URL**, the repository is cloned locally and then sent as the contex
    Remove intermediate containers after a successful build. The default is *true*.
 
 **-t**, **--tag**=""
-   Repository name (and optionally a tag) to be applied to the resulting image in case of success
+   Repository names (and optionally with tags) to be applied to the resulting image in case of success.
 
 **-m**, **--memory**=*MEMORY*
   Memory limit
@@ -235,6 +235,14 @@ If you do not provide a version tag then Docker will assign `latest`:
 
 When you list the images, the image above will have the tag `latest`.
 
+You can apply multiple tags to an image. For example, you can apply the `latest`
+tag to a newly built image and add another tag that references a specific
+version.
+For example, to tag an image both as `whenry/fedora-jboss:latest` and
+`whenry/fedora-jboss:v2.1`, use the following:
+
+    docker build -t whenry/fedora-jboss:latest -t whenry/fedora-jboss:v2.1 .
+
 So renaming an image is arbitrary but consideration should be given to 
 a useful convention that makes sense for consumers and should also take
 into account Docker community conventions.