Reformat kata --help

Currently `kata --help` will display a bunch of commands available to be run without any description and a bit confusing for people who don't have background. Inspired (again) by `kubectl`, reformat the help display with short description and useful grouping. Example from `kubectl`:

```
$ kubectl
kubectl controls the Kubernetes cluster manager.

Find more information at https://github.com/kubernetes/kubernetes.

Basic Commands (Beginner):
create Create a resource by filename or stdin
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
run Run a particular image on the cluster
run-container Run a particular image on the cluster
set Set specific features on objects

Basic Commands (Intermediate):
get Display one or many resources
explain Documentation of resources
edit Edit a resource on the server
delete Delete resources by filenames, stdin, resources and names, or by resources and label selector

Deploy Commands:
rollout Manage the rollout of a resource
rolling-update Perform a rolling update of the given ReplicationController
rollingupdate Perform a rolling update of the given ReplicationController
scale Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
resize Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController

Cluster Management Commands:
certificate Modify certificate resources.
cluster-info Display cluster info
clusterinfo Display cluster info
top Display Resource (CPU/Memory/Storage) usage.
cordon Mark node as unschedulable
uncordon Mark node as schedulable
drain Drain node in preparation for maintenance
taint Update the taints on one or more nodes

Troubleshooting and Debugging Commands:
describe Show details of a specific resource or group of resources
logs Print the logs for a container in a pod
attach Attach to a running container
exec Execute a command in a container
port-forward Forward one or more local ports to a pod
proxy Run a proxy to the Kubernetes API server
cp Copy files and directories to and from containers.
auth Inspect authorization

Advanced Commands:
apply Apply a configuration to a resource by filename or stdin
patch Update field(s) of a resource using strategic merge patch
replace Replace a resource by filename or stdin
update Replace a resource by filename or stdin
convert Convert config files between different API versions

Settings Commands:
label Update the labels on a resource
annotate Update the annotations on a resource
completion Output shell completion code for the specified shell (bash or zsh)

Other Commands:
api-versions Print the supported API versions on the server, in the form of "group/version"
config Modify kubeconfig files
help Help about any command
plugin Runs a command-line plugin
version Print the client and server version information

Use "kubectl --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
```