Autogenerate md documentation for kubectl

This does away with the giant dump from cobra for kubectl and instead
generates md files which contain similar information, but one per verb.
This might work well as part of the cobra project, instead of doing it
in kube, but this gets us nice, linked, documentation right now.  If
people like it, I will try to get something similar into cobra.

docs/kubectl-label.md

@@ -0,0 +1,69 @@
+## kubectl label
+
+Update the labels on a resource
+
+### Synopsis
+
+Update the labels on a resource.
+
+If --overwrite is true, then existing labels can be overwritten, otherwise attempting to overwrite a label will result in an error.
+If --resource-version is specified, then updates will use this resource version, otherwise the existing resource-version will be used.
+
+Examples:
+  $ kubectl label pods foo unhealthy=true
+  <update a pod with the label 'unhealthy' and the value 'true'>
+
+  $ kubectl label --overwrite pods foo status=unhealthy
+  <update a pod with the label 'status' and the value 'unhealthy' overwritting an existing value>
+  
+  $ kubectl label pods foo status=unhealthy --resource-version=1
+  <update a pod with the label 'status' and the value 'unhealthy' if the resource is unchanged from version 1>
+  
+  $ kubectl label pods foo bar-
+  <update a pod by removing a label named 'bar' if it exists. Does not require the --overwrite flag.>
+
+kubectl label [--overwrite] <resource> <name> <key-1>=<val-1> ... <key-n>=<val-n> [--resource-version=<version>]
+
+### Options
+
+```
+      --no-headers=false: When using the default output, don't print headers.
+  -o, --output="": Output format. One of: json|yaml|template|templatefile.
+      --output-version="": Output the formatted object with the given version (default api-version).
+      --overwrite=false: If true, allow labels to be overwritten, otherwise reject label updates that overwrite existing labels.
+      --resource-version="": If non-empty, the labels update will only succeed if this is the current resource-version for the object.
+  -t, --template="": Template string or path to template file to use when -o=template or -o=templatefile.
+```
+
+### Options inherrited from parent commands
+
+```
+      --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
+  -h, --help=false: help for kubectl
+      --insecure-skip-tls-verify=false: If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure.
+      --kubeconfig="": Path to the kubeconfig file to use for CLI requests.
+      --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.
+  -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
+      --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
+```
+
+### SEE ALSO
+* [kubectl](kubectl.md)
+