bundle plugin install need --path argument

[Whirlwind]

In the document (https://bundler.io/guides/bundler_plugins.html#install-a-plugin-from-your-gemfile), there are two ways to install a plugin: from a command or from your Gemfile.

Install a plugin from your Gemfile

plugin 'my_plugin', path: '/path/to/plugin' # Installs from a path

But, there is not a --path argument for bundle plugin install.

The doc said:

6. Running your plugin locally

To install and run your plugin locally, you can run bundler plugin install --git '/PATH/TO/GEM' copycat

But my plugin directory is not a git repository....

[deivid-rodriguez]

This will get fixed by #6960!