Knative Kn Plugin Source Kafka release v0.18.0

Initial plugin release.

This release of plugin the brings kafka source management capabilities with kn client.

Quick start:

• Download the plugin in your kn plugins directory (~/.config/kn/plugins)
• Rename the binary to kn-source-kafka and make it executable chmod u+x kn-source-kafka
• Verify if plugin is loaded: kn plugin list
• Run the plugin kn source kafka --help

➜ kn source kafka -h
Manage Knative kafka eventing sources

Usage:
  kafka [command]

Available Commands:
  create      Create a kafka source
  delete      Delete a kafka source
  describe    Describe a kafka source
  help        Help about any command

Flags:
  -h, --help   help for kafka

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