docs(cli): introduce examples in the kompose command

[martinjirku]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

This PR adds few basic examples to the cli command.

Which issue(s) this PR fixes:

Fixes #1717

Special notes for your reviewer:

I've considered to update Long instead adding the Examples field. However, it looked more clear to introduce these few examples. Maybe later, there will be more content to add into Long with specific examples.

The result of running kompose

Kompose is a tool to help users who are familiar with docker-compose move to Kubernetes.

Usage:
  kompose [command]

Examples:
  kompose --file compose.yaml convert
  kompose -f first.yaml -f second.yaml convert
  kompose --provider openshift --file compose.yaml convert
  kompose completion bash

Available Commands:
  completion  Output shell completion code
  convert     Convert a Docker Compose file
  help        Help about any command
  version     Print the version of Kompose

Flags:
      --error-on-warning    Treat any warning as an error
  -f, --file strings        Specify an alternative compose file
  -h, --help                help for kompose
      --provider string     Specify a provider. Kubernetes or OpenShift. (default "kubernetes")
      --suppress-warnings   Suppress all warnings
  -v, --verbose             verbose output

Use "kompose [command] --help" for more information about a command.

The result of kompose convert --help:

./kompose convert --help
Convert a Docker Compose file

Usage:
  kompose convert [flags]

Examples:
  kompose --file compose.yaml convert
  kompose -f first.yaml -f second.yaml convert
  kompose --provider openshift --file compose.yaml convert

Kubernetes Flags:
  -c, --chart                    Create a Helm chart for converted objects
      --controller               Set the output controller ("deployment"|"daemonSet"|"replicationController")
      --service-group-mode       Group multiple service to create single workload by "label"("kompose.service.group") or "volume"(shared volumes)
      --service-group-name       Using with --service-group-mode=volume to specific a final service name for the group

OpenShift Flags:
      --build-branch             Specify repository branch to use for buildconfig (default is current branch name)
      --build-repo               Specify source repository for buildconfig (default is current branch's remote url)
      --insecure-repository      Specify to use insecure docker repository while generating Openshift image stream object

Flags:
      --build string                 Set the type of build ("local"|"build-config"(OpenShift only)|"none") (default "none")
      --build-command string         Set the command used to build the container image. override the docker build command.Should be used in conjuction with --push-command flag.
      --controller string            Set the output controller ("deployment"|"daemonSet"|"replicationController")
      --generate-network-policies    Specify whether to generate network policies or not.
  -h, --help                         help for convert
      --indent int                   Spaces length to indent generated yaml files (default 2)
  -j, --json                         Generate resource files into JSON format
  -n, --namespace string             Specify the namespace of the generated resources
  -o, --out string                   Specify a file name or directory to save objects to (if path does not exist, a file will be created)
      --profile stringArray          Specify the profile to use, can use multiple profiles
      --push-command string          Set the command used to push the container image. override the docker push command. Should be used in conjuction with --build-command flag.
      --push-image                   If we should push the docker image we built
      --push-image-registry string   Specify registry for pushing image, which will override registry from image name.
      --pvc-request-size string      Specify the size of pvc storage requests in the generated resource spec
      --replicas int                 Specify the number of replicas in the generated resource spec (default 1)
      --secrets-as-files             Always convert docker-compose secrets into files instead of symlinked directories.
      --service-group-mode label     Group multiple service to create single workload by label(`kompose.service.group`) or `volume`(shared volumes)
      --service-group-name string    Using with --service-group-mode=volume to specific a final service name for the group
      --stdout                       Print converted objects to stdout
      --volumes string               Volumes to be generated ("persistentVolumeClaim"|"emptyDir"|"hostPath" | "configMap") (default "persistentVolumeClaim")
      --with-kompose-annotation      Add kompose annotations to generated resource (default true)

Global Flags:
      --error-on-warning    Treat any warning as an error
  -f, --file strings        Specify an alternative compose file
      --provider string     Specify a provider. Kubernetes or OpenShift. (default "kubernetes")
      --suppress-warnings   Suppress all warnings
  -v, --verbose             verbose output

[cdrage]

We've removed the voting and guestbook examples and we're trying to go away from using docker-compose.yml / .yml since compose is an open spec.

I think we should just put compose.yaml as even saying .yml is deprecated.

If that's good with you 👍

[martinjirku]

No worries, I will update it, so it will be consistent with the #1803.

[martinjirku]

Updated! 🎆

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cdrage, martinjirku

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[cdrage]

/lgtm