Add doc for ironcli aws-import subcommand.

docs/import.md

@@ -0,0 +1,37 @@
+Import existing AWS Lambda functions
+====================================
+
+The [ironcli](https://github.com/iron-io/ironcli/) tool includes a set of
+commands to act on Lambda functions. Most of these are described in
+[getting-started](./getting-started.md). One more subcommand is `aws-import`.
+
+If you have an existing AWS Lambda function, you can use this command to
+automatically convert it to a Docker image that is ready to be deployed on
+other platforms.
+
+### Credentials
+
+To use this, either have your AWS access key and secret key set in config
+files, or in environment variables. In addition, you'll want to set a default
+region. You can use the `aws` tool to set this up. Full instructions are in the
+[AWS documentation][awscli].
+
+[awscli]: http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html#cli-config-files
+
+### Importing
+
+Assuming you have a lambda function named `my-function`, the following command:
+
+```sh
+ironcli lambda aws-import my-function
+```
+
+will import the function code to a directory called `./my-function`. It will
+then create a docker image called `my-function`.
+
+If you only want to download the code, pass the `-download-only` flag. The
+`-region` and `-profile` flags are available similar to the `aws` tool to help
+you tweak the settings on a command level. If you want to call the docker image
+something other than `my-function`, pass the `-image <new name>` flag. Finally,
+you can import a different version of your lambda function than the latest one
+by passing `-version <version>.`

docs/introduction.md

@@ -41,6 +41,7 @@ guide](./getting-started.md). [Here is the environment](./environment.md) that
 Lambda provides. `ironcli lambda` lists the commands to work with Lambda
 functions locally.
 
+You can [import](./import.md) existing Lambda functions hosted on Amazon!
 The Docker environment required to run Lambda functions is described
 [here](./docker.md).