Create Actions Walkthrough (#36)

* starting walkthrough docs

* versioning

docs/container-action.md

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+# Creating a Docker Action
+
+The [container-template](https://github.com/actions/container-template) repo contains the base files to create a Docker action.
+
+# Create a Repo from the Template
+
+Navigate to https://github.com/actions/container-template
+
+Click on `Use this template` to create the repo for your action.
+
+![template](assets/node12-template.png)
+
+Complete creating your repo and clone the repo.
+
+> NOTE: The location of the repo will be how users will reference your action in their workflow file with the using keyword.
+
+e.g. To use https://github.com/actions/setup-node, user's will author:
+
+```yaml
+steps:
+    using: actions/setup-node@master
+```
+
+# Define Metadata
+
+Your action has a name and a description.  Update the author.
+
+Create inputs that your unit of work will need.  These will be what workflow authors set with the `with:` keyword.
+
+```yaml
+name: 'My Container Action'
+description: 'Get started with Container actions'
+author: 'GitHub'
+inputs: 
+  myInput:
+    description: 'Input to use'
+    default: 'world'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.myInput }}
+```
+
+It will be run with docker and the input is mapped into the args
+
+# Change Code
+
+The entry point is in entrypoint.sh
+
+```bash
+#!/bin/sh -l
+
+echo "hello $1"
+```
+
+# Publish 
+
+Simply push your action to publish.
+
+```bash
+$ git push
+```
+
+The runner will download the action and build the docker container on the fly at runtime.
+
+> Consider versioning your actions with tags.  See [versioning](docs/action-versioning.md)
+
+
+
+