Auto generation of markdown docs!

An example from the kubernetes project, for the `kubectl config`
command, which as subcommands, and flags, and all sorts of stuff, it
will generate markdown like so:

config modifies .kubeconfig files

config modifies .kubeconfig files using subcommands like "kubectl config set current-context my-context"

```
kubectl config SUBCOMMAND
```

```
      --envvar=false: use the .kubeconfig from $KUBECONFIG
      --global=false: use the .kubeconfig from /home/username
  -h, --help=false: help for config
      --kubeconfig="": use a particular .kubeconfig file
      --local=false: use the .kubeconfig in the current directory
```

```
      --alsologtostderr=false: log to standard error as well as files
      --api-version="": The API version to use when talking to the server
  -a, --auth-path="": Path to the auth info file. If missing, prompt the user. Only used if using https.
      --certificate-authority="": Path to a cert. file for the certificate authority.
      --client-certificate="": Path to a client key file for TLS.
      --client-key="": Path to a client key file for TLS.
      --cluster="": The name of the kubeconfig cluster to use
      --context="": The name of the kubeconfig context to use
      --insecure-skip-tls-verify=false: If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure.
      --log_backtrace_at=:0: when logging hits line file:N, emit a stack trace
      --log_dir=: If non-empty, write log files in this directory
      --log_flush_frequency=5s: Maximum number of seconds between log flushes
      --logtostderr=true: log to standard error instead of files
      --match-server-version=false: Require server version to match client version
      --namespace="": If present, the namespace scope for this CLI request.
      --password="": Password for basic authentication to the API server.
  -s, --server="": The address and port of the Kubernetes API server
      --stderrthreshold=2: logs at or above this threshold go to stderr
      --token="": Bearer token for authentication to the API server.
      --user="": The name of the kubeconfig user to use
      --username="": Username for basic authentication to the API server.
      --v=0: log level for V logs
      --validate=false: If true, use a schema to validate the input before sending it
      --vmodule=: comma-separated list of pattern=N settings for file-filtered logging
```

* [kubectl](kubectl.md)	 - kubectl controls the Kubernetes cluster manager
* [kubectl config set](kubectl_config_set.md)	 - Sets an individual value in a .kubeconfig file
* [kubectl config set-cluster](kubectl_config_set-cluster.md)	 - Sets a cluster entry in .kubeconfig
* [kubectl config set-context](kubectl_config_set-context.md)	 - Sets a context entry in .kubeconfig
* [kubectl config set-credentials](kubectl_config_set-credentials.md)	 - Sets a user entry in .kubeconfig
* [kubectl config unset](kubectl_config_unset.md)	 - Unsets an individual value in a .kubeconfig file
* [kubectl config use-context](kubectl_config_use-context.md)	 - Sets the current-context in a .kubeconfig file
* [kubectl config view](kubectl_config_view.md)	 - displays merged .kubeconfig settings or a specified .kubeconfig file.

md_docs.md

@@ -0,0 +1,35 @@
+# Generating Markdown Docs For Your Own cobra.Command
+
+## Generate markdown docs for the entire command tree
+
+This program can actually generate docs for the kubectl command in the kubernetes project
+
+```go
+package main
+
+import (
+	"io/ioutil"
+	"os"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/cmd"
+	"github.com/spf13/cobra"
+)
+
+func main() {
+	kubectl := cmd.NewFactory(nil).NewKubectlCommand(os.Stdin, ioutil.Discard, ioutil.Discard)
+	cobra.GenMarkdownTree(kubectl, "./")
+}
+```
+
+This will generate a whole series of files, one for each command in the tree, in the directory specified (in this case "./")
+
+## Generate markdown docs for a single command
+
+You may wish to have more control over the output, or only generate for a single command, instead of the entire command tree. If this is the case you may prefer to `GenMarkdown()` instead of `GenMarkdownTree`
+
+```go
+	out := new(bytes.Buffer)
+	cobra.GenMarkdown(cmd, out)
+```
+
+This will write the markdown doc for ONLY "cmd" into the out, buffer.