Quickstart plugin not findable by kn

[psschwei]

In an earlier Slack discussion, we noted that as is, the quickstart plugin is not found by the kn client when installed via Brew.

There were two potential solutions mentioned:

1. Install the plugin to ~/.config/kn/plugins
2. Default kn to look up from PATH as well

[csantanapr]

I'm confused about this because this repo already has plugins being install with brew like admin and source-kafka then how are people using this plugin being install in PATH if kn is unable to find them @rhuss

[maximilien]

kn has two methods for finding plugins: PATH and ~.config/kn/plugins. You can specify which you want with a config.yml or everytime you call kn (suboptimal)

[maximilien]

See issues #8 and #9