Audit reference docs and clean-up

[phanimarupaka]

This PR is to audit the overview reference doc. This is displayed when user types kpt and enter. There are many global flags which are inherited from kubectl. They should be cleaned as part of separating cli from live library.

[phanimarupaka]

➜  foo git:(main) ✗ kpt
Usage:
  kpt [flags]
  kpt [command]

Available Commands:
  fn          Transform and validate packages using containerized functions.
  help        Help about any command
  live        Reconcile configuration files with the live state
  pkg         Get, update, and describe packages with resources
  version     Print the version number of kpt

Not displaying flags here as they need more cleanup

➜  foo git:(main) ✗ kpt pkg
Usage:
  kpt pkg [flags]
  kpt pkg [command]

Aliases:
  pkg, package

Available Commands:
  cat         Print the resources in a file/directory
  diff        Show differences between a local package and upstream.
  get         Fetch a package from a git repo.
  init        Initialize an empty package.
  tree        Render resources using a tree structure
  update      Apply upstream package updates.

Flags:
  -h, --help   help for pkg

➜  foo git:(main) ✗ kpt fn
Usage:
  kpt fn [flags]
  kpt fn [command]

Aliases:
  fn, functions

Available Commands:
  doc         Display the documentation for a function
  eval        Locally execute one or more functions in containers
  export      Auto-generating function pipelines for different workflow orchestrators
  render      render
  sink        Specify a directory as an output sink package
  source      Specify a directory as an input source package

Flags:
  -h, --help   help for fn

➜  foo git:(main) ✗ kpt live
Usage:
  kpt live [flags]
  kpt live [command]

Available Commands:
  apply                  Apply a package to the cluster (create, update, prune).
  destroy                Remove all previously applied resources in a package from the cluster
  diff                   Display the diff between the local package and the live cluster resources.
  init                   Initialize a package with the information needed for inventory tracking.
  install-resource-group Install ResourceGroup custom resource definition as inventory object into APIServer
  migrate                Migrate inventory from ConfigMap to ResourceGroup custom resource
  preview                Preview the changes apply would make to the cluster
  status                 Display shows the status for the resources in the cluster

Not displaying flags here as they need more cleanup